Supplemental Prospectus (Form 424B5)

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-290865

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is in two parts. The first part is this prospectus supplement, which provides you with specific information regarding the terms of this offering and our Class A common stock, and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference in this prospectus supplement and the accompanying prospectus. The second part is the accompanying prospectus, which provides more general information, some of which does not apply to this offering.

Neither we nor the underwriters (or any of our or their affiliates) has authorized anyone to provide you with any information or to make any representations other than those contained in this prospectus supplement or the accompanying prospectus, or any free writing prospectus or subsequent prospectus supplement prepared by or on behalf of us or to which we have referred you. Neither we nor the underwriters (or any of our or their affiliates) takes any responsibility for, or provides any assurance as to the reliability of, any other information that others may give you. Neither we nor the underwriters (or any of our or their affiliates) will make an offer to sell these securities in any jurisdiction where the offer or sale is not permitted.

This prospectus supplement is not complete without the accompanying prospectus. This prospectus supplement should be read in conjunction with the prospectus, which is to be delivered with this prospectus supplement, and is qualified by reference thereto, except to the extent that the information in this prospectus supplement updates or supersedes the information contained in the prospectus. The prospectus includes other information about our business, financial condition and risk factors you should consider before making any investment in our securities.

We are subject to the informational requirements of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and therefore file reports and other information with the United States Securities and Exchange Commission ("SEC"). Statements contained in this prospectus supplement and the accompanying prospectus about the provisions or contents of any agreement or other document are only summaries. If SEC rules require that any agreement or document be filed as an exhibit to the registration statement of which the accompanying prospectus forms a part, you should refer to that agreement or document for its complete contents.

The information contained or incorporated by reference in this prospectus supplement, the accompanying prospectus or any related free writing prospectus prepared by us is accurate only as of the date of this prospectus supplement or the date of the accompanying prospectus, as applicable, regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or of any sale of our Class A common stock. Our business, financial condition, results of operations and prospects may have changed since those dates.

If the description of this offering varies between this prospectus supplement and the accompanying prospectus, you should rely on the information in this prospectus supplement. Any statement made in this prospectus supplement or in a document incorporated or deemed to be incorporated by reference in this prospectus supplement will be deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement or in any other subsequently filed document that is also incorporated or deemed to be incorporated by reference in this prospectus supplement modifies or supersedes that statement. Any statement so modified or superseded will not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement.

Unless otherwise indicated, information contained in this prospectus supplement concerning our industry and the markets in which we operate, including our general expectations, market position and market opportunity, is based on our management's estimates and research, as well as industry and general publications and research, surveys and studies conducted by third parties. Our management's estimates are derived from publicly available information, their knowledge of our industry and their assumptions based on such information and knowledge, which we believe to be reasonable. While we believe the industry, market and competitive

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position data included in this prospectus supplement is reliable and based on reasonable assumptions, we have not independently verified data from third-party sources. This data involves a number of assumptions and limitations which are necessarily subject to a high degree of uncertainty and risk due to a variety of factors. These and other factors could cause results to differ materially from those expressed in the estimates made by the third parties and by us.

This prospectus supplement includes references to trademarks, service marks and trade names that we use in connection with the operation of our business, including without limitation, Guardian Pharmacy, Guardian Pharmacy Services, GuardianShield, Guardian Compass and our logos, which are our property and are protected under applicable intellectual property laws. This prospectus supplement also may contain trademarks, service marks and trade names of other companies, which are the property of their respective owners. Solely for convenience, the trademarks, service marks and trade names referred to in this prospectus supplement are referred to without the TM, SM and ^® symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto.

As used in this prospectus supplement, unless otherwise indicated or the context otherwise requires, references to "we," "us," "our," "Guardian," the "Company" or similar terms refer to Guardian Pharmacy Services, Inc. Statements regarding the number of residents we served as of a given date reflect the number of residents served during the last month of the period ending on such date.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Forward-looking statements are all statements other than those of historical fact. Any statements about our expectations, beliefs, plans, predictions, forecasts, objectives, assumptions, or future events or performance are not historical facts and may be forward-looking. These statements are often, but not always, made through the use of words such as "aims," "anticipates," "believes," "contemplates," "continues," "estimates," "expects," "intends," "may," "outlook," "plans," "seeks," "should," "will," "would," and similar expressions. Although we believe that the expectations reflected in these forward-looking statements are reasonable, these statements are not guarantees of future performance and involve risks and uncertainties which are subject to change based on various important factors, many of which are beyond our control. Among the factors that could cause actual results to differ materially from those suggested by forward-looking statements are:

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New risks and uncertainties emerge from time to time, and it is not possible for us to predict all risks and uncertainties that could have an impact on the forward-looking statements contained in this prospectus supplement. The results, events and circumstances reflected in the forward-looking statements may not be achieved or occur, and actual results, events or circumstances could differ materially from those described in, or implied by, the forward-looking statements. Therefore, we caution you not to place undue reliance on any forward-looking statements or information. Any forward-looking statements speak only as of the date of this prospectus supplement. We undertake no obligation to update any forward-looking statements made in this prospectus supplement to reflect events or circumstances after the date of this prospectus supplement or to reflect new information or the occurrence of unanticipated events, except as may be required by law.

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RISK FACTORS

Investing in our Class A common stock involves a high degree of risk. You should carefully consider the risks and uncertainties described below, together with all of the other information in this prospectus supplement and the accompanying prospectus, including our consolidated financial statements and related notes, before deciding whether to invest in our Class A common stock. See the section of this prospectus supplement entitled "Incorporation by Reference." Any of the following risks could materially and adversely affect our business, financial condition, results of operations and prospects. In that event, the market price of our Class A common stock could decline, and you could lose part or all of your investment.

Risks Related to Ownership of Our Class A Common Stock and this Offering

The Guardian Founders are able to exercise significant control over us, including through the election of all of our directors.

The Guardian Founders, consisting of Bindley Capital Partners I, LLC ("Bindley Capital"), Pharmacy Investors, LLC, Cardinal Equity Fund, L.P., Fred Burke, David Morris and Kendall Forbes, beneficially own, and immediately following the completion of this offering and the Synthetic Secondary, are expected to continue to beneficially own, shares of our common stock representing a majority of our combined voting power. Pursuant to the terms of the Stockholders' Agreement, the Guardian Founders have the ability to elect all of the members of our board of directors and thereby control our management and affairs. Accordingly, the Guardian Founders are able to determine the outcome of substantially all matters requiring action by our stockholders, including amendments to our amended and restated certificate of incorporation ("certificate of incorporation") and bylaws, any proposed merger, consolidation or sale of all or substantially all of our assets and other corporate transactions even if such actions are not favored by our other stockholders. This concentration of ownership may also prevent a change in the composition of our board of directors or a change in control of the Company that could deprive our stockholders of an opportunity to receive a premium for their Class A common stock as part of a sale of the Company and might ultimately affect the market price of our Class A common stock.

Our future issuance of Class A common stock, Class B common stock, preferred stock or convertible debt securities could dilute our common stockholders and adversely affect the market value of our Class A common stock.

The future issuance of shares of Class A common stock, Class B common stock, preferred stock or convertible debt securities may dilute the economic and voting rights of our stockholders and reduce the market price of the Class A common stock. Preferred stock, if issued, could have a preference with respect to liquidating distributions or a preference with respect to dividend payments that could limit our ability to pay dividends to the holders of our Class A common stock and adversely affect the market price of the Class A common stock.

From time to time in the future, we may also issue additional shares of our Class A common stock or securities convertible into Class A common stock pursuant to a variety of transactions, including acquisitions. We also anticipate that we may issue shares of our Class B common stock as consideration in the buyout of minority owners in our future greenfield start-up pharmacies and future acquired pharmacies. The issuance by us of additional shares of our Class A common stock, Class B common stock or securities convertible into our Class A common stock may dilute your ownership of us and the sale of a significant amount of such shares in the public market could adversely affect prevailing market prices of our Class A common stock.

The market price of shares of our Class A common stock has experienced, and may in the future experience, substantial volatility.

As a company with a relatively limited public float, shares of our Class A common stock may experience greater stock price volatility, price run-ups, lower trading volumes, large spreads in bid and ask prices and less

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liquidity than companies with larger capitalizations. Such volatility, including any stock run-ups, may be unrelated to our actual or expected operating performance, results of operations, financial condition or prospects, making it difficult for prospective investors to assess the rapidly changing value of our Class A common stock.

In addition, if the trading volumes of our Class A common stock are low, persons buying or selling in relatively small quantities may easily influence the price of our Class A common stock. This low volume of trades could also cause the price of our Class A common stock to fluctuate greatly, with large percentage changes in price occurring in any particular trading day session. Holders of our Class A common stock may also not be able to readily liquidate their investment or may be forced to sell at depressed prices due to low volume trading. Broad market fluctuations and general economic and political conditions may also adversely affect the market price of our Class A common stock. As a result of this volatility, investors may experience losses on their investment in our Class A common stock. A decline in the market price of our Class A common stock could also adversely affect our ability to issue additional shares of Class A common stock or other of our securities and our ability to obtain additional financing in the future. No assurance can be given that an active market in our Class A common stock will develop or be sustained. If an active market does not develop, holders of our Class A common stock may be unable to readily sell the shares they hold or may not be able to sell their shares at all.

Future sales, or the perception of future sales of Class A common stock, by us or our existing stockholders in the public market following this offering could cause the market price for our common stock to decline.

The sale of substantial amounts of shares of our Class A common stock in the public market, including in this offering or future issuances of additional shares of Class A common stock or additional "synthetic secondary" transactions, or the perception that such sales could occur, could harm the prevailing market price of shares of our Class A common stock. These sales, or the possibility that these sales may occur, also might make it more difficult for us to sell equity securities in the future at a time and at a price that we deem appropriate. Upon completion of this offering, we will have outstanding a total of 36,259,762 shares of our Class A common stock (assuming that we repurchase 1,020,000 shares of Class A common stock in the Synthetic Secondary), and 27,060,872 shares of Class B common stock convertible into Class A common stock on a one-to-one basis. Shares of Class A common stock sold or issued in this offering will be freely tradable without restriction or further registration under the Securities Act.

The 27,060,872 shares of Class B common stock outstanding immediately following this offering will continue to be subject to certain transfer restrictions and conversion terms, including with respect to sales. These transfer restrictions will cease to apply as shares of Class B common stock automatically convert into shares of Class A common stock over the two-year period following their respective dates of issuance. In addition, our board of directors may accelerate the conversion of Class B common stock into Class A common stock at their discretion. In addition, in connection with this offering, we and all of our directors and executive officers, and the selling stockholders will enter into lock-up agreements with the underwriters that will, subject to certain customary exceptions, restrict the sale of the shares of our common stock and certain other securities held by them for 180 days following the date of this prospectus supplement. The underwriters may, in their sole discretion and at any time, release all or any portion of the shares or securities subject to any such lock-up agreements. Further, pursuant to the stock purchase agreements we have entered into with the stockholders from whom we will repurchase 1,020,000 shares of Class A common stock in the Synthetic Secondary, all other shares of common stock held by them will be subject to lock-up restrictions for 180 days following the date of this prospectus supplement.

If securities or industry analysts do not publish research or reports about our business, or if they downgrade their recommendations regarding our Class A common stock, the Class A common stock price and trading volume could decline.

The trading market for our Class A common stock will be influenced by the research and reports that industry or securities analysts publish about us or our business. If any of the analysts who cover us downgrades

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our Class A common stock or publishes inaccurate or unfavorable research about our business, our Class A common stock price may decline. If analysts cease coverage of us or fail to regularly publish reports on us, we could lose visibility in the financial markets, which in turn could cause our Class A common stock trading volume to decline and our Class A common stock to be less liquid and result in a decline in the stock price of our Class A common stock.

We do not intend to pay any cash dividends on our common stock in the foreseeable future.

Following the completion of this offering, we do not expect to pay any dividends on our common stock in the foreseeable future. Payments of future dividends, if any, will be at the discretion of our board of directors after taking into account various factors, including our business, operating results and financial condition, current and anticipated cash needs, plans for expansion and any legal or contractual limitations on our ability to pay dividends. As a result, capital appreciation in the price of our Class A common stock, if any, may be your only source of gain on an investment in our Class A common stock.

We are a holding company with no operations of its own and, accordingly, we depend on our subsidiaries for cash to fund our operations and expenses, including future dividend payments, if any.

We are a holding company and have no material assets other than our ownership of equity interests in our operating subsidiaries. As a holding company, we have no independent means of generating revenue, and our principal source of cash flow will be distributions from our subsidiaries. Therefore, our ability to fund and conduct our business, service our debt, and pay dividends, if any, in the future will depend on the ability of our subsidiaries to generate sufficient cash flow to make upstream cash distributions to us. Our subsidiaries are separate legal entities, and although they are wholly owned or majority owned and controlled by us, they have no obligation to make any funds available to us, whether in the form of loans, dividends, or otherwise. The ability of our subsidiaries to distribute cash to us will also be subject to, among other things, restrictions that may be contained in our subsidiary agreements (as entered into from time to time), availability of sufficient funds in such subsidiaries and applicable laws and regulatory restrictions. Claims of any creditors of our subsidiaries generally will have priority as to the assets of such subsidiaries over our claims and claims of our creditors and stockholders. To the extent the ability of our subsidiaries to distribute dividends or other payments to us is limited in any way, our ability to fund and conduct our business, pay our expenses, service our debt, and pay dividends, if any, could be harmed.

Our certificate of incorporation and bylaws and provisions of Delaware law may discourage or prevent certain strategic transactions, including a takeover of our company, even if such a transaction would be beneficial to our stockholders.

Provisions contained in our certificate of incorporation and bylaws and provisions of the Delaware General Corporation Law (the "DGCL"), could delay or prevent a third party from entering into a strategic transaction with us, even if such a transaction would benefit our stockholders. For example, our certificate of incorporation and bylaws:

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In addition, we are subject to the provisions of Section 203 of the DGCL which limits, subject to certain exceptions, the right of a corporation to engage in a business combination with a holder of 15% or more of the corporation's outstanding voting securities, or certain affiliated persons.

These restrictions and provisions could keep us from pursuing relationships with strategic partners and from raising additional capital, which could impede our ability to expand our business and strengthen our competitive position.

Our certificate of incorporation designates the Court of Chancery of the State of Delaware as the exclusive forum for certain litigation that may be initiated by our stockholders and the federal district courts of the United States as the exclusive forum for litigation arising under the Securities Act, which could limit our stockholders' ability to obtain a favorable judicial forum for disputes with us or our directors, officers or employees.

Our certificate of incorporation provides that, unless we consent in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, the federal district court for the District of Delaware) will be the sole and exclusive forum for (i) any derivative action or proceeding brought on our behalf, (ii) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or other employees to us or our stockholders, (iii) any action asserting a claim arising pursuant to any provision of the DGCL or our certificate of incorporation or bylaws (as either may be amended from time to time), or (iv) any action asserting a claim governed by the internal affairs doctrine.

Furthermore, our certificate of incorporation also provides that, unless we consent in writing to the selection of an alternative forum, the federal district courts of the United States will be, to the fullest extent permitted by law, the sole and exclusive forum for any action asserting a claim arising under the Securities Act. However, Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all suits brought to enforce a duty or liability created by the Securities Act or the rules and regulations thereunder and accordingly, we cannot be certain that a court would enforce such provision. We believe this provision would not apply to any action or proceeding asserting a claim under the Exchange Act.

Our certificate of incorporation further provides that, to the fullest extent permitted by law, any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock will be deemed to have notice of, and consented to, the provisions of our certificate of incorporation described above. However, our stockholders will not be deemed to have waived our compliance with the federal securities laws and the rules and regulations thereunder. The forum selection provisions in our certificate of incorporation may have the effect of discouraging lawsuits against us or our directors, officers or employees and may limit our stockholders' ability to obtain a favorable judicial forum for disputes with us or our directors, officers or employees, and may increase the costs associated with bringing a claim, which may disadvantage a stockholder in any such lawsuit. If the enforceability of our forum selection provision were to be challenged, we may incur additional costs associated with resolving such a challenge. While we currently have no basis to expect any such challenge would be successful, if a court were to find our forum selection provision to be inapplicable or unenforceable, we may incur additional costs associated with having to litigate in other jurisdictions, which could have an adverse effect on our business, financial condition and results of operations and result in a diversion of the time, resources and attention of our management.

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USE OF PROCEEDS

We estimate the net proceeds to us from our sale of shares of Class A common stock in this offering will be approximately $34.8 million, based on the assumed public offering price of $34.09 per share, which is the last reported sale price of our Class A common stock on the NYSE on March 17, 2026, and after deducting the underwriting discount but before deducting any estimated expenses payable by us in connection with this offering.

We intend to use the net proceeds to us from our sale of shares of Class A common stock in this offering to purchase in the Synthetic Secondary 1,020,000 shares of Class A common stock that were issued upon conversion of shares of our Class B common stock that were originally issued in connection with our Corporate Reorganization. The purchase price per share of shares of Class A common stock purchased in the Synthetic Secondary will be equal to the public offering price per share of Class A common stock in this offering, less the underwriting discount. Following our repurchase of shares of Class A common stock in connection with the Synthetic Secondary, we do not expect to have any remaining net proceeds from this offering.

Guardian will not receive any proceeds from the sale of shares by the selling stockholders in this offering. The selling stockholders will bear the underwriting discounts attributable to their sale of shares of Class A common stock in this offering.

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SELLING STOCKHOLDERS

The following table sets forth information concerning the beneficial ownership of our common stock, as of March 13, 2026, by each of the selling stockholders. The beneficial ownership information is presented on the following bases: (1) prior to this offering and the Synthetic Secondary; and (2) after giving effect to this offering and the Company's purchase of 1,020,000 shares of Class A common stock in the Synthetic Secondary.

Unless otherwise indicated in the footnotes below, the address of each selling stockholder is c/o Guardian Pharmacy Services, Inc., 300 Galleria Parkway S.E., Suite 800, Atlanta, Georgia 30339. The following percentages are based on an aggregate 63,320,634 shares of common stock outstanding, consisting of 36,259,762 shares of Class A common stock outstanding and 27,060,872 shares of Class B common stock outstanding.

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MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERS

The following discussion is a summary of material U.S. federal income tax considerations generally applicable to the ownership and disposition of our Class A common stock by a Non-U.S. Holder (as defined below) that acquires our Class A common stock pursuant to this offering and that holds our Class A common stock as a capital asset within the meaning of section 1221 of the Internal Revenue Code of 1986, as amended (the "Code") (generally, property held for investment). This discussion is based on the Code, Treasury Department regulations promulgated thereunder ("Regulations"), judicial decisions, administrative pronouncements and other relevant applicable authorities, all as currently in effect as of the date hereof and all of which are subject to change or differing interpretations (possibly with retroactive effect).

This discussion does not address all U.S. federal income tax considerations that may be applicable to Non-U.S. Holders in light of their particular circumstances or Non-U.S. Holders subject to special treatment under U.S. federal income tax law, such as (without limitation):

In addition, this discussion does not address any U.S. state or local or non-U.S. tax considerations or any U.S. federal estate, gift, alternative minimum tax, Medicare contribution tax considerations, the rules regarding qualified small business stock within the meaning of section 1202 of the Code, or any election to apply section 1400Z-2 of the Code to gains recognized with respect to shares of our Class A common stock. Non-U.S. Holders should consult their tax advisors regarding the particular tax considerations to them of owning and disposing of our Class A common stock.

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For purposes of this discussion, a "Non-U.S. Holder" is a beneficial owner of our Class A common stock that is not for U.S. federal income tax purposes:

If a partnership (or other entity or arrangement treated as a partnership or other pass-through entity for U.S. federal income tax purposes) holds our Class A common stock, the tax treatment of a partner or beneficial owner of the entity will generally depend on the status of the owner and the activities of the entity. Partners in a partnership (or beneficial owners of another entity or arrangement treated as a partnership or other pass-through entity for U.S. federal income tax purposes) should consult their tax advisors regarding the tax considerations of an investment in our Class A common stock.

THIS DISCUSSION IS FOR INFORMATIONAL PURPOSES ONLY AND IS NOT TAX ADVICE. INVESTORS CONSIDERING THE PURCHASE, OWNERSHIP, AND DISPOSITION OF OUR COMMON STOCK ARE URGED TO CONSULT THEIR OWN TAX ADVISORS REGARDING THE APPLICATION OF U.S. FEDERAL INCOME TAX LAWS TO THEIR PARTICULAR SITUATIONS AND THE CONSEQUENCES OF OTHER FEDERAL, STATE, LOCAL, AND FOREIGN TAX LAWS, AND APPLICABLE TAX TREATIES.

Distributions on Our Class A Common Stock

As discussed under the section titled "Dividend Policy," we do not currently anticipate paying dividends to our Class A common stockholders. In the event that we do make distributions of cash or property (other than certain stock distributions) with respect to our Class A common stock (or that we engage in certain redemptions that are treated as distributions with respect to Class A common stock), any such distributions generally will be treated as dividends to the extent paid from our current or accumulated earnings and profits (as determined under U.S. federal income tax principles). If a distribution exceeds our current and accumulated earnings and profits (as determined under U.S. federal income tax principles), the excess will be treated first as a tax-free return of capital to the extent of a Non-U.S. Holder's adjusted tax basis in our Class A common stock and thereafter as capital gain from the sale, exchange or other taxable disposition of our Class A common stock, with the tax treatment described below in "-Sale, Exchange or Other Disposition of Our Class A Common Stock."

Subject to the discussions below under "-Backup Withholding and Information Reporting" and "-Foreign Account Tax Compliance Act Withholding Taxes," and the discussion regarding effectively connected income in the next paragraph, distributions treated as dividends paid on our Class A common stock to a Non-U.S. Holder will generally be subject to U.S. federal withholding tax at a 30% rate, or a reduced rate specified by an applicable income tax treaty. In order to obtain a reduced rate of withholding under an applicable income tax treaty, a Non-U.S. Holder will generally be required to provide to us or another applicable withholding agent a properly executed Internal Revenue Service ("IRS") Form W-8BEN or IRS Form W-8BEN-E or other applicable IRS Form W-8 (or any appropriate successor or replacement forms), as applicable, together with any necessary attachments, certifying qualification for such reduced rate. If the Non-U.S. Holder holds the stock through a financial institution or other agent acting on the Non-U.S. Holder's behalf, the Non-U.S. Holder will be required to provide appropriate documentation to the agent. Even if our current or accumulated earnings or profits are less

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than the amount of the distribution, the applicable withholding agent may elect to treat the entire distribution as a dividend for U.S. federal withholding tax purposes. A Non-U.S. Holder that does not timely furnish the required documentation but that is eligible for a reduced rate of U.S. federal withholding tax pursuant to an income tax treaty generally may obtain a refund of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

Subject to the discussions below under "-Backup Withholding and Information Reporting" and "-Foreign Account Tax Compliance Act Withholding Taxes," no amounts in respect of U.S. federal withholding tax will be withheld from dividends paid to a Non-U.S. Holder if the dividends are effectively connected with such Non-U.S. Holder's conduct of a trade or business within the United States (and, if required by an applicable income tax treaty, are attributable to a permanent establishment or fixed base maintained by such Non-U.S. Holder in the United States) and the Non-U.S. Holder provides to us or another applicable withholding agent a properly executed IRS Form W-8ECI certifying such exemption. Instead, the effectively connected dividends will generally be subject to regular U.S. federal income tax on a net income basis as if the Non-U.S. Holder were a U.S. person as defined under the Code. A Non-U.S. Holder that is treated as a corporation for U.S. federal income tax purposes receiving effectively connected dividends may also be subject to an additional "branch profits tax" imposed at a rate of 30% (or a lower treaty rate) on its effectively connected earnings and profits (subject to certain adjustments).

Sale, Exchange or Other Disposition of Our Class A Common Stock

Subject to the discussions below under "-Backup Withholding and Information Reporting" and "-Foreign Account Tax Compliance Act Withholding Taxes," a Non-U.S. Holder will generally not be subject to U.S. federal income tax on gain realized on a sale, exchange or other disposition of our Class A common stock unless:

Although there can be no assurance in this regard, we believe that we are not a USRPHC and we do not anticipate becoming a USRPHC for U.S. federal income tax purposes. Non-U.S. Holders are urged to consult their own tax advisors about the consequences that could result if we are, or become, a USRPHC.

Backup Withholding and Information Reporting

Payments of dividends on our Class A common stock will not be subject to backup withholding, provided a Non-U.S. Holder either certifies to such Non-U.S. Holder's non-U.S. status, such as by furnishing a valid IRS Form W-8BEN, W-8BEN-E, or W-8ECI, or other applicable IRS Form W-8, or otherwise establishes an exemption. However, information returns are required to be filed with the IRS in connection with any dividends

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on our Class A common stock paid to a Non-U.S. Holder, regardless of whether any tax was actually withheld. In addition, proceeds of the sale or other taxable disposition of our Class A common stock within the United States or conducted through certain U.S.-related brokers generally will not be subject to backup withholding or information reporting, if the applicable withholding agent receives the certification described above or a Non-U.S. Holder otherwise establishes an exemption. Proceeds of a disposition of our Class A common stock conducted through a non-U.S. office of a non-U.S. broker generally will not be subject to backup withholding or information reporting. Payments of dividends on our Class A common stock and proceeds of a disposition of our Class A common stock may be subject to additional information reporting and may also be subject to U.S. federal backup withholding if such Non-U.S. Holder fails to comply with applicable U.S. information reporting and certification requirements.

Copies of information returns that are filed with the IRS may also be made available under the provisions of an applicable treaty or agreement to tax authorities in a Non-U.S. Holder's country of residence, establishment, or organization.

Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules maybe allowed as a refund or credit against a Non-U.S. Holder's U.S. federal income tax liability, provided that the required information is furnished to the IRS in a timely manner.

Foreign Account Tax Compliance Act Withholding Taxes

Certain rules may require withholding at a rate of 30% on dividends in respect of, and (subject to the proposed Regulations discussed below) the gross proceeds from the sale or other disposition of, our Class A common stock held by or through certain foreign financial institutions (which is broadly defined for this purpose and includes investment funds), unless such institution (i) enters into, and complies with, an agreement with the Treasury Department to report, on an annual basis, information with respect to interests in, and accounts maintained by, the institution to the extent such interests or accounts are held by certain U.S. persons and by certain non-U.S. entities that are wholly or partially owned by U.S. persons and to withhold on certain payments or (ii) complies with an intergovernmental agreement between the United States and an applicable foreign country to report such information to its local tax authority, which will exchange such information with the U.S. authorities. An intergovernmental agreement between the United States and an applicable foreign country may modify these requirements. Accordingly, the entity through which our Class A common stock is held will affect the determination of whether such withholding is required. Similarly, dividends in respect of, and (subject to the proposed Regulations discussed below) the gross proceeds from the sale or other disposition of, our Class A common stock held by an investor that is a non-financial non-U.S. entity that does not qualify under certain exemptions will be subject to withholding at a rate of 30%, unless such entity either (i) certifies that such entity does not have any "substantial United States owners" or (ii) provides certain information regarding the entity's "substantial United States owners," which we or the applicable withholding agent will in turn provide to the Treasury Department. The Treasury Department has released proposed Regulations which, if finalized in their present form, would eliminate the application of this regime with respect to payments of gross proceeds (but not dividends). Pursuant to these proposed Regulations, we and any other applicable withholding agent may (but are not required to) rely on this proposed change to Foreign Account Tax Compliance Act withholding until final regulations are issued or until such proposed regulations are rescinded. We will not pay any amounts to holders in respect of any amounts withheld. Non-U.S. Holders should consult their tax advisors regarding the possible implications of this withholding tax on their investment in our Class A common stock.

THE PRECEDING DISCUSSION OF U.S. FEDERAL INCOME TAX CONSEQUENCES IS FOR GENERAL INFORMATION ONLY. IT IS NOT TAX ADVICE. EACH PROSPECTIVE INVESTOR IS URGED TO CONSULT ITS OWN TAX ADVISOR REGARDING THE PARTICULAR U.S. FEDERAL, STATE, LOCAL, AND FOREIGN TAX CONSEQUENCES OF PURCHASING, OWNING, AND DISPOSING OF OUR COMMON STOCK, INCLUDING THE CONSEQUENCES OF ANY PROPOSED CHANGE IN APPLICABLE LAWS AND TREATIES.

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UNDERWRITING

BofA Securities, Inc. and Jefferies LLC are acting as representatives of each of the underwriters named below. Subject to the terms and conditions set forth in an underwriting agreement among us, the selling stockholders and the underwriters, we and the selling stockholders have agreed to sell to the underwriters, and each of the underwriters has agreed, severally and not jointly, to purchase, the number of shares of Class A common stock set forth opposite its name below.

Subject to the terms and conditions set forth in the underwriting agreement, the underwriters have agreed, severally and not jointly, to purchase all of the shares sold under the underwriting agreement if any of these shares are purchased. If an underwriter defaults, the underwriting agreement provides that the purchase commitments of the nondefaulting underwriters may be increased or the underwriting agreement may be terminated.

We and the selling stockholders have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act, or to contribute to payments the underwriters may be required to make in respect of those liabilities.

The underwriters are offering the shares, subject to prior sale, when, as and if issued to and accepted by them, subject to approval of legal matters by their counsel, including the validity of the shares, and other conditions contained in the underwriting agreement, such as the receipt by the underwriters of officer's certificates and legal opinions. The underwriters reserve the right to withdraw, cancel or modify offers to the public and to reject orders in whole or in part.

Commissions and Discounts

The representatives have advised us and the selling stockholders that the underwriters propose initially to offer the shares to the public at the public offering price set forth on the cover page of this prospectus supplement and to dealers at that price less a concession not in excess of $     per share. After the initial offering, the public offering price, concession or any other term of the offering may be changed.

The following table shows the public offering price, underwriting discount and proceeds before expenses to us and the selling stockholders. The information assumes either no exercise or full exercise by the underwriters of their option to purchase additional shares.

The expenses of the offering, not including the underwriting discount, are estimated at $     and are payable by us.

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Option to Purchase Additional Shares

The selling stockholders have granted an option to the underwriters, exercisable for 30 days after the date of this prospectus supplement, to purchase up to 750,000 additional shares at the public offering price, less the underwriting discount. If the underwriters exercise this option, each will be obligated, subject to conditions contained in the underwriting agreement, to purchase a number of additional shares proportionate to that underwriter's initial amount reflected in the above table.

No Sales of Similar Securities

Subject to customary exceptions, we and all of our directors, executive officers and the selling stockholders have agreed, for a period of 180 days after the date of this prospectus, not to directly or indirectly offer, sell, contract to sell or otherwise dispose of or transfer any shares or any securities convertible into or exchangeable for shares of our capital stock, without the prior written consent of the representative. Following the expiration of such lock-up restrictions and the conversion of their shares of Class B common stock, our executive officers and directors and certain of our other existing security holders, subject to compliance with the Securities Act or exceptions therefrom, will be able to freely trade their Class A common stock. These lock-up restrictions also preclude any hedging, collar or other transaction designed or reasonably expected to result in a disposition of shares of common stock or securities convertible into or exercisable or exchangeable for shares of common stock. BofA Securities, Inc. and Jefferies LLC may, in their sole discretion and at any time, release all or any portion of the securities subject to these restrictions. BofA Securities Inc. and Jefferies LLC do not have any present intent or any understanding to release all or any portion of the securities subject to these restrictions.

In connection with this offering and the Synthetic Secondary, effective on March 18, 2026, we entered into stock purchase agreements with certain holders of shares of Class A common stock that were issued upon conversion of shares of our Class B common stock that were originally issued in connection with our Corporate Reorganization. After giving effect to the Synthetic Secondary, these holders have agreed that they will not offer, sell, contract to sell, pledge, grant any option to purchase, distribute, or otherwise dispose of any shares of common stock held by them (collectively, a "Disposition") for a period of 180 days from the date of this prospectus (the "Lock-up Period") without the prior written consent of the Company (which consent the Company has agreed it will not provide without receiving the prior written consent of BofA Securities, Inc. and Jefferies LLC).

In addition, each holder of Class B common stock is subject to certain extended transfer restrictions pursuant to our certificate of incorporation. Shares of Class B common stock may not be transferred by the holder thereof, unless such transfer is a Permitted Transfer. Our certificate of incorporation provides that shares of Class B common stock will automatically convert on a one-for-one basis into shares of Class A common stock over a two-year period. See "Description of Capital Stock-General-Transfer Restrictions and Conversion of Class B Common Stock" in the accompanying prospectus.

New York Stock Exchange Listing

The shares are listed on the New York Stock Exchange under the symbol "GRDN."

Price Stabilization, Short Positions

Until the distribution of the shares is completed, SEC rules may limit underwriters and selling group members from bidding for and purchasing our common stock. However, the representatives may engage in transactions that stabilize the price of the common stock, such as bids or purchases to peg, fix or maintain that price.

In connection with the offering, the underwriters may purchase and sell our common stock in the open market. These transactions may include short sales, purchases on the open market to cover positions created by

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short sales and stabilizing transactions. Short sales involve the sale by the underwriters of a greater number of shares than they are required to purchase in the offering. "Covered" short sales are sales made in an amount not greater than the underwriters' option to purchase additional shares described above. The underwriters may close out any covered short position by either exercising their option to purchase additional shares or purchasing shares in the open market. In determining the source of shares to close out the covered short position, the underwriters will consider, among other things, the price of shares available for purchase in the open market as compared to the price at which they may purchase shares through the option granted to them. "Naked" short sales are sales in excess of such option. The underwriters must close out any naked short position by purchasing shares in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of our common stock in the open market after pricing that could adversely affect investors who purchase in the offering. Stabilizing transactions consist of various bids for or purchases of shares of common stock made by the underwriters in the open market prior to the completion of the offering.

Similar to other purchase transactions, the underwriters' purchases to cover the syndicate short sales may have the effect of raising or maintaining the market price of our common stock or preventing or retarding a decline in the market price of our common stock. As a result, the price of our common stock may be higher than the price that might otherwise exist in the open market. The underwriters may conduct these transactions on the New York Stock Exchange, in the over-the-counter market or otherwise.

Neither we nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of our common stock. In addition, neither we nor any of the underwriters make any representation that the representatives will engage in these transactions or that these transactions, once commenced, will not be discontinued without notice.

Electronic Distribution

In connection with the offering, certain of the underwriters or securities dealers may distribute prospectuses by electronic means, such as e-mail.

Other Relationships

Some of the underwriters and their affiliates have engaged in, and may in the future engage in, investment banking and other commercial dealings in the ordinary course of business with us or our affiliates. They have received, or may in the future receive, customary fees and commissions for these transactions.

In addition, in the ordinary course of their business activities, the underwriters and their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers. Such investments and securities activities may involve securities and/or instruments of ours or our affiliates. The underwriters and their affiliates may also make investment recommendations and/or publish or express independent research views in respect of such securities or financial instruments and may hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

Selling Restrictions

Notice to Prospective Investors in the European Economic Area

In relation to each Member State of the European Economic Area (each, a "Relevant State"), no shares have been offered or will be offered pursuant to the offering to the public in that Relevant State prior to the publication of a prospectus in relation to the shares which has been approved by the competent authority in that Relevant State or, where appropriate, approved in another Relevant State and notified to the competent authority

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in that Relevant State, all in accordance with the Prospectus Regulation, except that offers of shares may be made to the public in that Relevant State at any time under the following exemptions under the Prospectus Regulation:

provided that no such offer of shares shall require us or any representative to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation. Each person who initially acquires any shares or to whom any offer is made will be deemed to have represented, acknowledged, and agreed to and with each of the underwriters and the Company that it is a "qualified investor" within the meaning of Article 2(e) of the Prospectus Regulation. In the case of any shares being offered to a financial intermediary as that term is used in Article 5(1) of the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged, and agreed that the shares acquired by it in the offer have not been acquired on a nondiscretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer of any shares to the public other than their offer or resale in a Relevant State to qualified investors as so defined or in circumstances in which the prior consent of the representative has been obtained to each such proposed offer or resale.

The Company, the representative and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements and agreements.

For the purposes of this provision, the expression an "offer to the public" in relation to any shares in any Relevant State means the communication in any form and by any means of sufficient information on the terms of the offer and any shares to be offered so as to enable an investor to decide to purchase or subscribe for any shares, and the expression "Prospectus Regulation" means Regulation (EU) 2017/1129 (as amended).

This selling restriction is in addition to any other selling restrictions set out below.

Notice to Prospective Investors in the United Kingdom

In relation to the United Kingdom, no shares have been offered or will be offered pursuant to this offering to the public in the United Kingdom prior to the publication of a prospectus in relation to the shares that either (1) has been approved by the Financial Conduct Authority or (2) is to be treated as if it had been approved by the Financial Conduct Authority in accordance with the transitional provisions in Article 74 of the Prospectus (Amendment etc.) (EU Exit) Regulations 2019, except that offers of shares may be made to the public in the United Kingdom at any time under the following exemptions under the UK Prospectus Regulation:

provided that no such offer of shares shall require us or any representative to publish a prospectus pursuant to section 85 of the FSMA or supplement a prospectus pursuant to Article 23 of the UK Prospectus Regulation and each person who initially acquires any shares or to whom any offer is made will be deemed to have represented, acknowledged, and agreed to and with each of the underwriters and us that it is a "qualified investor" within the meaning of Article 2(e) of the UK Prospectus Regulation.

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The Company, the representative and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements and agreements.

For the purposes of this provision, the expression an "offer to the public" in relation to any shares in the United Kingdom means the communication in any form and by any means of sufficient information on the terms of the offer and any shares to be offered so as to enable an investor to decide to purchase or subscribe for any shares, and the expression "UK Prospectus Regulation" means Regulation (EU) 2017/1129 as it forms part of domestic law by virtue of the European Union (Withdrawal) Act 2018, as amended.

We have not authorized and do not authorize the making of any offer of shares through any financial intermediary on our or the underwriters' behalf, other than offers made by the underwriters with a view to the final placement of the shares as contemplated in this prospectus. Accordingly, no purchaser of the shares, other than the underwriters, is authorized to make any further offer of the shares on behalf of us or the underwriters.

In addition, this document is being distributed only to, and is directed only at, (i) persons who are outside the United Kingdom, (ii) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the "Order"), or (iii) high net worth companies, and other persons to whom it may be lawfully communicated, falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as "relevant persons").

The shares are only available to, and any invitation, offer, or agreement to subscribe, purchase, otherwise acquire such shares will be engaged in only with, relevant persons. Any person who is not a relevant person should not act or rely on this document or any of its contents.

Notice to Prospective Investors in Canada

The shares may be sold in Canada only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions, and Ongoing Registrant Obligations. Any resale of the shares must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser's province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser's province or territory of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts ("NI 33-105"), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

Notice to Prospective Investors in Switzerland

This prospectus supplement is not intended to constitute an offer or solicitation to purchase or invest in the shares. The shares may not be publicly offered, directly or indirectly, in Switzerland within the meaning of the Swiss Financial Services Act ("FinSA") and will not be listed on the SIX Swiss Exchange ("SIX") or on any other stock exchange or regulated trading venue (exchange or multilateral trading facility) in Switzerland. This document does not constitute a prospectus within the meaning of, and has been prepared without regard to, the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or

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the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading venue (exchange or multilateral trading facility) in Switzerland. Neither this document nor any other offering or marketing material relating to the shares constitutes a prospectus pursuant to the FinSA, and neither this document nor any other offering or marketing material relating to the shares or this offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to this offering, the Company, or the shares have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of shares will not be supervised by, the Swiss Financial Market Supervisory Authority, and the offer of shares has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes ("CISA"). The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of shares.

Notice to Prospective Investors in Australia

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission ("ASIC"), in relation to this offering. This document:

The shares may not be directly or indirectly offered for subscription or purchased or sold, and no invitations to subscribe for or buy the shares may be issued, and no draft or definitive offering memorandum, advertisement, or other offering material relating to any shares may be distributed in Australia, except where disclosure to investors is not required under Chapter 6D of the Corporations Act or is otherwise in compliance with all applicable Australian laws and regulations. By submitting an application for the shares, you represent and warrant to us that you are an Exempt Investor.

As any offer of shares under this document will be made without disclosure in Australia under Chapter 6D.2 of the Corporations Act, the offer of those securities for resale in Australia within twelve months may, under section 707 of the Corporations Act, require disclosure to investors under Chapter 6D.2 if none of the exemptions in section 708 applies to that resale. By applying for the shares you undertake to us that you will not, for a period of twelve months from the date of issue of the shares, offer, transfer, assign, or otherwise alienate those shares to investors in Australia except in circumstances where disclosure to investors is not required under Chapter 6D.2 of the Corporations Act or where a compliant disclosure document is prepared and lodged with ASIC.

This document contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this document is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

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Notice to Prospective Investors in Hong Kong

The shares have not been offered or sold and will not be offered or sold in Hong Kong by means of any document other than (1) to "professional investors" as defined in the Securities and Futures Ordinance (Cap. 571 of the Laws of Hong Kong) (the "SFO") and any rules made thereunder, or (2) in other circumstances which do not result in the document being a "prospectus" as defined in the Companies (Winding Up and Miscellaneous Provisions) Ordinance (Cap. 32 of the Laws of Hong Kong).

No advertisement, invitation or document relating to the shares has been or may be issued or has been or may be in the possession of any person for the purpose of issue (in each case whether in Hong Kong or elsewhere), which is directed at, or the contents of which are likely to be accessed or read by, the public in Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to shares which are or are intended to be disposed of only to persons outside Hong Kong or only to "professional investors" in Hong Kong as defined in the SFO and any rules made thereunder.

Notice to Prospective Investors in Japan

No registration pursuant to Article 4, paragraph 1 of the Financial Instruments and Exchange Act of Japan (Law No. 25 of 1948, as amended) (the "FIEA") has been made or will be made with respect to the solicitation of the application for the acquisition of the shares. Accordingly, the shares have not been, directly or indirectly, offered or sold and will not be, directly or indirectly, offered or sold in Japan or to, or for the benefit of, any resident of Japan (which term as used herein means any person resident in Japan, including any corporation or other entity organized under the laws of Japan) or to others for re-offering or re-sale, directly or indirectly, in Japan or to, or for the benefit of, any resident of Japan except pursuant to an exemption from the registration requirements, and otherwise in compliance with, the FIEA and the other applicable laws and regulations, directives, and ministerial guidelines of Japan.

Notice to Prospective Investors in Singapore

This document has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this document and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the shares may not be circulated or distributed, nor may the shares be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (1) to an institutional investor (as defined under Section 4A of the Securities and Futures Act, Chapter 289 of Singapore (the "SFA")) under Section 274 of the SFA, (2) to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions specified in Section 275 of the SFA or (3) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA, in each case subject to conditions set forth in the SFA.

Where the shares are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

the securities or securities-based derivative contracts (each as defined in Section 2(1) of the SFA) of that corporation or the beneficiaries' rights and interest (howsoever described) in that trust shall not be transferable for six months after that corporation or that trust has acquired the shares under Section 275 of the SFA except:

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Any reference to the SFA is a reference to the Securities and Futures Act 2001 of Singapore, and a reference to any term as defined in the SFA or any provision in the SFA is a reference to that term or provision as modified or amended from time to time including by such of its subsidiary legislation as may be applicable at the relevant time.

Notice to Prospective Investors in the Dubai International Financial Centre

This document relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority ("DFSA") (an "Exempt Offer"). This document is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this document nor taken steps to verify the information set forth herein and has no responsibility for the document. The shares to which this document relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the shares offered should conduct their own due diligence on the shares. If you do not understand the contents of this document, you should consult an authorized financial advisor.

In relation to its use in the Dubai International Financial Centre ("DIFC"), this document is strictly private and confidential and is being distributed to a limited number of investors and must not be provided to any person other than the original recipient, and may not be reproduced or used for any other purpose. The interests in the securities may not be offered or sold directly or indirectly to the public in the DIFC.

Notice to Prospective Investors in the United Arab Emirates

The shares have not been, and are not being, publicly offered, sold, promoted, or advertised in the United Arab Emirates (including the DIFC) other than in compliance with the laws of the United Arab Emirates (and the DIFC) governing the issue, offering, and sale of securities. Further, this document does not constitute a public offer of securities in the United Arab Emirates (including the DIFC) and is not intended to be a public offer. This document has not been approved by or filed with the Central Bank of the United Arab Emirates, the Securities and Commodities Authority, or the DFSA.

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INCORPORATION BY REFERENCE

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a web site at https://www.sec.gov that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC, including us.

The SEC allows us to "incorporate by reference" into this prospectus supplement the information we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus supplement, and later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings made with the SEC under Section 13(a), 13(c), 14 and 15(d) of the Exchange Act (other than any documents or portions of such documents that are furnished rather than filed with the SEC), until our offering is completed:

You may request a copy of any or all of the information that has been incorporated by reference into this prospectus supplement but not delivered with this prospectus supplement at no cost by writing to or telephoning us at the following address:

Guardian Pharmacy Services, Inc.

300 Galleria Parkway SE, Suite 800

Atlanta, GA 30339

Phone: 404-810-0089

Email: [email protected].

We maintain an Internet site at https://www.guardianpharmacy.com which contains information concerning Guardian and its subsidiaries. The information contained at our Internet site is not incorporated by reference in this prospectus supplement or the accompanying prospectus, and you should not consider it a part of this prospectus supplement or the accompanying prospectus.

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LEGAL MATTERS

The validity of the issuance of the shares of Class A common stock offered hereby will be passed upon for us by Jones Day, Atlanta, Georgia. Mayer Brown LLP, New York, New York is representing the underwriters in connection with this offering.

EXPERTS

The consolidated financial statements of Guardian Pharmacy Services, Inc. appearing in Guardian Pharmacy Services, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2025, and the effectiveness of Guardian Pharmacy Services, Inc.'s internal control over financial reporting as of December 31, 2025, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon included therein, and incorporated herein by reference. Such financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the report of Ernst & Young LLP pertaining to such financial statements and the effectiveness of our internal control over financial reporting as of the respective dates (to the extent covered by consents filed with the Securities and Exchange Commission) given on the authority of such firm as experts in accounting and auditing.

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PROSPECTUS

Up to 1,020,000 Shares of Class A Common Stock

Up to 4,980,000 Shares of Class A Common Stock Offered by Selling Stockholders

This prospectus is part of a registration statement that Guardian Pharmacy Services, Inc. ("Guardian", the "Company," "we," "us," or "our") filed with the U.S. Securities and Exchange Commission (the "SEC") under a "shelf" registration process. Under this process, we may offer and sell up to an aggregate of 1,020,000 shares of our Class A common stock, par value, $0.001 per share ("Class A common stock"), and the selling stockholders named in this prospectus or in a prospectus supplement may offer and sell up to an aggregate of 4,980,000 shares of our Class A common stock, at any time and from time to time, in one or more offerings. We will not receive any proceeds from the sale of shares of our Class A common stock by the selling stockholders.

This prospectus provides you with a general description of our Class A common stock that we may offer. Each time we, or any of the selling stockholders, offer and sell Class A common stock described in this prospectus, we or such selling stockholders will provide a supplement to this prospectus that contains specific information about the offering and, if applicable, the selling stockholders, as well as the amounts and prices of the Class A common stock to be offered and sold. The applicable prospectus supplement may also add, update or change information contained in this prospectus with respect to that offering. You should read this prospectus and any accompanying prospectus supplement, together with the additional information in the section of this prospectus entitled "Where You Can Find More Information and Incorporation by Reference," carefully before deciding whether to invest in our Class A common stock. This prospectus may not be used to make sales of offered securities unless accompanied by a prospectus supplement or a free writing prospectus.

We or the selling stockholders may offer and sell the Class A common stock described in this prospectus and any prospectus supplement to or through one or more underwriters, dealers, and agents, or directly to purchasers, or through a combination of these methods. If any underwriters, dealers, or agents are involved in the sale of our Class A common stock, their names and any applicable purchase price, fee, commission, or discount arrangement between or among them will be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement. See the section of this prospectus entitled "Plan of Distribution" for more information.

Our Class A common stock is listed on the New York Stock Exchange ("NYSE") under the symbol "GRDN." On November 3, 2025, the last sale price of Guardian's Class A common stock as reported on the NYSE was $28.27 per share.

We have not authorized anyone to provide you with information that is different from, or in addition to, the information provided in this prospectus or any later prospectus supplement. We are not making an offer to sell securities in any state or country where the offer is not permitted.

Investing in Guardian's Class A common stock involves risks. See "Risk Factors" on page 4 of this prospectus.

Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is November 3, 2025.

TABLE OF CONTENTS

i

ABOUT THIS PROSPECTUS

Basis of Presentation

As used in this prospectus, unless otherwise indicated or the context otherwise requires, references to "we," "us," "our," "Guardian," the "Company" or similar terms refer to Guardian Pharmacy Services, Inc. References to our certificate of incorporation and bylaws refer to our amended and restated certificate of incorporation and amended and restated bylaws. Statements regarding the number of residents we served as of a given date reflect the number of residents served during the last month of the period ending on such date.

Industry and Market Data

Unless otherwise indicated, information contained in this prospectus concerning our industry and the markets in which we operate, including our general expectations, market position and market opportunity, is based on our management's estimates and research, as well as industry and general publications and research, surveys and studies conducted by third parties. Our management's estimates are derived from publicly available information, their knowledge of our industry and their assumptions based on such information and knowledge, which we believe to be reasonable. While we believe the industry, market and competitive position data included in this prospectus is reliable and based on reasonable assumptions, we have not independently verified data from third-party sources. This data involves a number of assumptions and limitations which are necessarily subject to a high degree of uncertainty and risk due to a variety of factors. These and other factors could cause results to differ materially from those expressed in the estimates made by the third parties and by us.

Trademarks, Service Marks and Trade Names

This prospectus includes references to trademarks, service marks and trade names that we use in connection with the operation of our business, including without limitation, Guardian Pharmacy, Guardian Pharmacy Services, GuardianShield, Guardian Compass and our logos, which are our property and are protected under applicable intellectual property laws. This prospectus also may contain trademarks, service marks and trade names of other companies, which are the property of their respective owners. Solely for convenience, the trademarks, service marks and trade names referred to in this prospectus are referred to without the TM, SM and ^® symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act"), and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). Forward-looking statements are all statements other than those of historical fact. Any statements about our expectations, beliefs, plans, predictions, forecasts, objectives, assumptions, or future events or performance are not historical facts and may be forward-looking. These statements are often, but not always, made through the use of words such as "aims," "anticipates," "believes," "contemplates," "continues," "estimates," "expects," "intends," "may," "plans," "seeks," "should," "will," "would," and similar expressions. Although we believe that the expectations reflected in these forward-looking statements are reasonable, these statements are not guarantees of future performance and involve risks and uncertainties which are subject to change based on various important factors, many of which are beyond our control. Among the factors that could cause actual results to differ materially from those suggested by forward-looking statements are:

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New risks and uncertainties emerge from time to time, and it is not possible for us to predict all risks and uncertainties that could have an impact on the forward-looking statements contained in this prospectus. The results, events and circumstances reflected in the forward-looking statements may not be achieved or occur, and actual results, events or circumstances could differ materially from those described in, or implied by, the forward-looking statements. Therefore, we caution you not to place undue reliance on any forward-looking statements or information. Any forward-looking statements speak only as of the date of this prospectus. We undertake no obligation to update any forward-looking statements made in this prospectus to reflect events or circumstances after the date of this prospectus or to reflect new information or the occurrence of unanticipated events, except as may be required by law.

WHERE YOU CAN FIND MORE INFORMATION AND INCORPORATION BY REFERENCE

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a web site at https://www.sec.gov that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC, including us.

The SEC allows us to "incorporate by reference" into this prospectus the information we file with it, which means that we can disclose important information to you by referring you to those documents. The information

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incorporated by reference is considered to be part of this prospectus, and later information that we file with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings made with the SEC under Section 13(a), 13(c), 14 and 15(d) of the Exchange Act (other than any documents or portions of such documents that are furnished rather than filed with the SEC), until our offering is completed:

You may request a copy of any or all of the information that has been incorporated by reference into this prospectus but not delivered with the prospectus at no cost by writing to or telephoning us at the following address:

Guardian Pharmacy Services, Inc.

300 Galleria Parkway SE, Suite 800

Atlanta, GA 30339

Phone: 404-810-0089

Email: [email protected].

We maintain an Internet site at https://www.guardianpharmacy.com which contains information concerning Guardian and its subsidiaries. The information contained at our Internet site is not incorporated by reference in this prospectus, and you should not consider it a part of this prospectus.

ABOUT GUARDIAN

We are a leading, highly differentiated pharmacy services company that provides an extensive suite of technology-enabled services designed to help residents of LTCFs adhere to their appropriate drug regimen, which in turn helps reduce the cost of care and improve clinical outcomes. We enter into contracts directly with LTCFs to serve as the principal pharmacy provider for their residents. In this capacity, we offer high-touch, individualized clinical, drug dispensing and administration capabilities that are tailored to serve the needs of residents in historically lower acuity LTCFs, such as assisted living facilities ("ALFs") and behavioral health facilities ("BHFs"). Additionally, our robust capabilities enable us to serve residents in all types of LTCFs. Our services include prescription intake and adjudication management, packaging drugs into unit dose and/or multi-dose compliance packaging that are organized by date and time of administration, and electronically tracking each drug from delivery through administration to LTCF residents. We also offer training to caregivers and conduct mock audits to ensure compliance with pharmacy administration requirements, billing claims processing, government regulation and other matters. As of June 30, 2025, our 52 pharmacies served approximately 195,000 residents in approximately 7,400 LTCFs across 38 states.

While our national competitors have primarily focused on skilled nursing facilities ("SNFs"), we believe we enjoy a strong competitive position as a large and purpose-built provider of pharmacy services to ALFs and

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BHFs. More than two-thirds of our annual revenue for each of the past three years has been generated from residents of ALFs and BHFs, while the remainder has been generated primarily from residents of SNFs. LTCF industry trends, including aging demographics, increases in the number of assisted living residents, improving life expectancies and enhanced quality of care, have resulted in ALF and BHF resident populations that require assistance with their increasingly acute and complex healthcare needs. Through our value-added capabilities and local management model, we have been able to pass on to residents, LTCFs and health plan payors the benefits of our scale without compromising on the high-touch, localized customer service traditionally associated with an independent pharmacy. For this reason, we are well positioned to continue to serve ALFs and BHFs, which we believe to be the most attractive and highest growth sector of the LTCF market.

Our core growth strategy focuses on increasing the number of residents we serve through a combination of organic and acquired growth. Acquired growth represents growth in the number of residents served resulting from acquiring an operating pharmacy, which we measure using the number of residents served by the acquired pharmacy as of the acquisition date. Organic growth represents the increase in the number of residents served at existing pharmacies, our greenfield pharmacies, and acquired pharmacies subsequent to the acquisition date. We have generated organic growth through new and expanded LTCF relationships as well as increased resident adoption of our services in the facilities we already serve.

We have two classes of common stock outstanding: Class A common stock and Class B common stock, par value $0.001 per share ("Class B common stock"). The rights of the holders of Class A common stock and Class B common stock are identical, except for certain transfer restrictions and conversion terms applicable to Class B common stock. Each share of Class A common stock and Class B common stock entitles its holder to one vote on all matters presented to our stockholders generally.

As of September 30, 2025, we had outstanding an aggregate of 36,253,744 shares of Class A common stock and 27,066,890 shares of Class B common stock. In accordance with the terms of our amended and restated certificate of incorporation, 13,521,419 and 13,521,396 outstanding shares of Class B common stock, issued on September 27, 2024 in connection with our corporate reorganization and initial public offering, will convert on a one-for-one basis into shares of Class A common stock on March 28, 2026 and September 27, 2026, respectively.

Corporate Information

Our principal executive offices are located at 300 Galleria Parkway SE, Suite 800, Atlanta, Georgia 30339. Our telephone number is (404) 810-0089. Our website is http://www.guardianpharmacy.com. The information contained on or accessible through our website is not part of this prospectus, other than the documents that we file with the SEC that are specifically incorporated by reference into this prospectus.

RISK FACTORS

Before deciding whether to invest in any of our securities, in addition to the other information included or incorporated by reference in this prospectus and any applicable prospectus supplement, you should carefully consider the risk factors under the heading "Part I-Item 1A. Risk Factors" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, which are incorporated herein by reference. These risk factors may be amended, supplemented or superseded from time to time by:

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In addition, new risks may emerge at any time and we cannot predict such risks or estimate the extent to which they may affect our financial performance. See "Special Note Regarding Forward-Looking Statements" and "Where You Can Find More Information and Incorporation by Reference."

USE OF PROCEEDS

We intend to use the net proceeds from the sale of the Class A common stock offered by us as set forth in any applicable prospectus supplement. We will not receive any proceeds from the sale of shares of our Class A common stock by any selling stockholders.

DESCRIPTION OF CAPITAL STOCK

The following is a description of the material terms of, and is qualified in its entirety by, our amended and restated certificate of incorporation and amended and restated bylaws. the forms of which are filed as exhibits to the registration statement of which this prospectus forms a part. Accordingly, references herein to our certificate of incorporation and bylaws refer to our certificate of incorporation and bylaws as so amended and restated. Because this is only a summary, it may not contain all the information that is important to you. Under "Description of Capital Stock," "we," "us," "our" and the "Company" refer to Guardian Pharmacy Services, Inc. and not to any of its subsidiaries.

General

Our authorized capital stock consists of 700,000,000 shares of Class A common stock, par value $0.001 per share, 100,000,000 shares of Class B common stock, par value $0.001 per share and 50,000,000 shares of preferred stock, par value $0.001 per share. Unless our board of directors determines otherwise, we will issue all shares of our capital stock in uncertificated form.

We have two classes of common stock: Class A common stock, which has one vote per share, and Class B common stock, which has one vote per share. The Class A common stock and Class B common stock vote together as a single class on all matters submitted to a vote of stockholders (including the election of directors), except as otherwise required by applicable law and except in connection with amendments to our certificate of incorporation that increase or decrease the par value of the shares of such class, or alter or change the powers, preferences or special rights of the shares of either class so as to affect the holders of such shares adversely

Voting

Holders of shares of our Class A common stock and Class B common stock are entitled to one vote for each share held of record on all matters on which stockholders are entitled to vote generally, including the election or removal of directors elected by our stockholders. The holders of our Class A common stock and Class B common stock do not have cumulative voting rights in the election of directors.

Dividends

Holders of shares of our Class A common stock and Class B common stock are entitled to receive dividends when, as and if declared by our board of directors out of funds legally available therefor, subject to any statutory or contractual restrictions on the payment of dividends and to any restrictions on the payment of dividends imposed by the terms of any outstanding preferred stock. See "Dividend Policy."

Liquidation

Upon our liquidation, dissolution or winding up and after payment in full of all amounts required to be paid to creditors and to the holders of preferred stock having liquidation preferences, if any, the holders of shares of

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our Class A common stock and Class B common stock will be entitled to receive ratably our remaining assets available for distribution, unless different treatment of the shares of each such class is approved by the affirmative vote of the holders of a majority of the outstanding shares of Class A common stock and Class B common stock, each voting separately as a class.

Fully Paid and Non-Assessable

All shares of our Class A common stock and Class B common stock are fully paid and non-assessable. The Class A common stock and Class B common stock are not subject to further calls or assessments by us.

Rights and Preferences

Holders of shares of our Class B common stock do not have preemptive, subscription or redemption rights. Shares of our Class B common stock are convertible into shares of our Class A common stock as described below under "-Transfer Restrictions and Conversion of Class B Common Stock."

There are no redemption or sinking fund provisions applicable to the Class A common stock or Class B common stock. The rights powers, preferences and privileges of our Class A common stock and Class B common stock will be subject to those of the holders of any shares of our preferred stock or any other series or class of stock we may authorize and issue in the future.

Transfer Restrictions and Conversion of Class B Common Stock

Shares of Class B common stock may not be transferred by the holder thereof, unless such transfer is a "Permitted Transfer." We refer to a transferee of shares of Class B common stock received in a Permitted Transfer as a "Permitted Transferee." In accordance with our certificate of incorporation, a "Permitted Transfer" generally includes any transfer of Class B common stock (i) approved in advance by our board of directors; (ii) to a family member of the holder; (iii) to certain entities owned by the holder or certain trusts (each, a "Permitted Entity"); (iv) upon a holder's death by will, intestate succession or operation of law; or (v) by a Permitted Entity to a family member of the holder or any other Permitted Entity of the holder.

As provided in our certificate of incorporation, with respect to each holder of Class B common stock (and any subsequent Permitted Transferee) (a "Qualified Stockholder"), such holder's shares of Class B common stock will automatically convert into shares of Class A common stock on a one-for-one basis pursuant to the two-year conversion schedule set forth in our certificate of incorporation. We refer to the date of issuance of the relevant shares of Class B common stock as the "Class B Issuance Date." With respect to each holder being issued shares of Class B common stock on the Class B Issuance Date, 25% of such holder's shares of Class B common stock will convert into shares of Class A common stock on each of the following dates: (i) the date that is 6 months after the Class B Issuance Date; (ii) the date of the one-year anniversary of the Class B Issuance Date; (iii) the date that is 18 months after the Class B Issuance Date; and (iv) the date of the two-year anniversary of the Class B Issuance Date.

If the conversion of any shares of Class B common stock would result in the conversion of any fractional share, the number of shares so converted will be rounded down to the nearest whole number. Notwithstanding the foregoing conversion terms, our board of directors may accelerate the conversion of all or any portion of Class B common stock to earlier times, including to permit participation of holders of Class B common stock in underwritten secondary public offerings or for any other reason.

Preferred Stock

No shares of preferred stock are currently issued or outstanding. Our certificate of incorporation authorizes our board of directors to establish one or more series of preferred stock (including convertible preferred stock).

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Unless required by law or any stock exchange, the authorized shares of preferred stock will be available for issuance without further action by the holders of our Class A common stock or Class B common stock. Our board of directors is able to determine, with respect to any series of preferred stock, the powers (including voting powers), preferences and relative, participating, optional or other special rights, and the qualifications, limitations or restrictions thereof, including, without limitation:

We could issue a series of preferred stock that could, depending on the terms of the series, impede or discourage an acquisition attempt or other transaction that some, or a majority, of the holders of our common stock might believe to be in their best interests or in which the holders of our Class A common stock might receive a premium over the market price of the shares of our Class A common stock. Additionally, the issuance of preferred stock may adversely affect the rights of holders of our Class A common stock by restricting dividends on the Class A common stock, diluting the voting power of the common stock or subordinating the liquidation rights of the Class A common stock. As a result of these or other factors, the issuance of preferred stock could have an adverse impact on the market price of our Class A common stock.

Annual Stockholders Meetings

Our bylaws provide that annual stockholder meetings will be held at a date, time and place, if any, as selected by our board of directors. To the extent permitted under applicable law, we may conduct meetings by remote communications, including by webcast.

Anti-Takeover Effects of Our Certificate of Incorporation and Bylaws and Certain Provisions of Delaware Law

Our certificate of incorporation and bylaws contain, and the DGCL contains, provisions that are intended to avoid costly takeover battles, reduce our vulnerability to a hostile or abusive change of control and enhance the ability of our board of directors to maximize stockholder value in connection with any unsolicited offer to acquire us. These provisions may have an anti-takeover effect and may delay, deter or prevent a merger or acquisition of Guardian by means of a tender offer, a proxy contest or other takeover attempt that a stockholder

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might consider in its best interest, including those attempts that might result in a premium over the prevailing market price for the shares of Class A common stock held by stockholders.

Authorized but Unissued Capital Stock

The authorized but unissued shares of common stock and preferred stock will be available for future issuance without stockholder approval, subject to any limitations imposed by the listing standards of NYSE. These additional shares may be used for a variety of corporate finance transactions, acquisitions and employee benefit plans. The existence of authorized but unissued and unreserved common stock and preferred stock could make more difficult or discourage an attempt to obtain control of us by means of a proxy contest, tender offer, merger or otherwise.

Business Combinations

We are governed by Section 203 of the DGCL. In general, Section 203 of the DGCL prohibits a publicly held Delaware corporation from engaging in a business combination transaction with an interested stockholder (a stockholder who purchases more than 15% of our common stock) for a period of three years after the interested stockholder became such unless the transaction fits within an applicable exemption, such as board approval of the business combination or the transaction that resulted in such stockholder becoming an interested stockholder. These provisions apply even if the business combination could be considered beneficial by some stockholders and may have the effect of delaying, deferring or preventing a change in control.

No Cumulative Voting

Under Delaware law, the right to vote cumulatively does not exist unless the certificate of incorporation specifically authorizes cumulative voting. Our certificate of incorporation does not authorize cumulative voting. Therefore, stockholders holding a majority of the shares of our stock entitled to vote generally in the election of directors will be able to elect all our directors.

Special Stockholder Meetings

Our certificate of incorporation and bylaws provide that special meetings of our stockholders may be called at any time only by or at the direction of a majority of the directors or the chairman of the board of directors. Our certificate of incorporation and bylaws prohibit the conduct of any business at a special meeting other than as specified in the notice for such meeting. These provisions may have the effect of deferring, delaying, or discouraging hostile takeovers, or changes in control or management of Guardian.

Stockholder Proposals and Director Nominations

Our bylaws establish advance notice procedures with respect to stockholder proposals and stockholders' nomination of candidates for election as directors. In order for any matter to be "properly brought" before a meeting, a stockholder must comply with advance notice requirements and provide us with certain information. Generally, to be timely, a stockholder's notice must be received at our principal executive offices not less than 90 days nor more than 120 days prior to the first anniversary date of the immediately preceding annual meeting of stockholders. Our bylaws also specify requirements as to the form and content of a stockholder's notice. Our bylaws allow the chairman of the meeting at a meeting of the stockholders to adopt rules and regulations for the conduct of meetings that may have the effect of precluding the conduct of certain business at a meeting if the rules and regulations are not followed. These provisions may also defer, delay, or discourage a potential acquirer from conducting a solicitation of proxies to elect the acquirer's own slate of directors or otherwise attempting to influence or obtain control of Guardian.

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Stockholder Action by Written Consent

Our certificate of incorporation provides that so long as we are a "controlled company" within the meaning of the rules or regulations of any stock exchange applicable to the Company, any action required or permitted to be taken by our stockholders may be effected by written consent. Our certificate of incorporation provides that, after we cease to be a "controlled company," our stockholders may not take action by written consent but may only take action at annual or special meetings of our stockholders. This provision may lengthen the amount of time required to take stockholder actions and would prevent the amendment of our bylaws or removal of directors by our stockholders without holding a meeting of stockholders.

Dissenters' Rights of Appraisal and Payment

Under the DGCL, with certain exceptions, our stockholders will have appraisal rights in connection with a merger or consolidation of us. Pursuant to the DGCL, stockholders who properly request and perfect appraisal rights in connection with such merger or consolidation will have the right to receive payment of the fair value of their shares as determined by the Delaware Court of Chancery.

Stockholders' Derivative Actions

Under the DGCL, any of our stockholders may bring an action in our name to procure a judgment in our favor, also known as a derivative action, provided that the stockholder bringing the action is a holder of our shares at the time of the transaction to which the action relates or such stockholder's stock thereafter devolved by operation of law.

Choice of Forum

Unless we consent to the selection of an alternative forum, the Court of Chancery of the State of Delaware is, to the fullest extent permitted by law, the sole and exclusive forum for any derivative action or proceeding brought on our behalf; any action asserting a claim of breach of fiduciary duty owed by any of our directors, officers, or other employees to us or to our stockholders; any action asserting a claim against us arising pursuant to the DGCL or our certificate of incorporation or bylaws; or any action asserting a claim against us that is governed by the internal affairs doctrine.

In addition, unless we consent to the selection of an alternative forum, the federal district courts of the United States of America is the exclusive forum for the resolution of any complaint asserting a cause of action arising under the Securities Act. However, we believe such forum selection provision would not apply to claims brought to enforce a duty or liability created by the Exchange Act.

Officers and Directors

The DGCL authorizes corporations to limit or eliminate the personal liability of directors and officers to corporations and their stockholders for monetary damages for breaches of fiduciary duties, subject to certain exceptions. Our certificate of incorporation includes a provision that eliminates the personal liability of directors and officers for monetary damages to the corporation or its stockholders for any breach of fiduciary duty or other act or omission as a director, except to the extent such exemption from liability or limitation thereof is not permitted under the DGCL. The effect of these provisions is to eliminate the rights of us and our stockholders, through stockholders' derivative suits on our behalf, to recover monetary damages from a director or officer for breach of fiduciary duty, including breaches resulting from grossly negligent behavior. However, exculpation does not apply to any breaches of the director's or officer's duty of loyalty, any acts or omissions not in good faith or that involve intentional misconduct or knowing violation of law, to any director for any authorization of dividends or stock redemptions or repurchases paid or made in violation of the DGCL, for any transaction from which the director or officer derived an improper personal benefit, or to any officer in any action by or in the right of the corporation.

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Our bylaws generally provide that we must indemnify and advance expenses to our directors and officers to the fullest extent authorized by the DGCL. We also are expressly authorized to carry directors' and officers' liability insurance providing indemnification for our directors, officers and certain employees for some liabilities. We believe that these indemnification and advancement provisions and insurance are useful to attract and retain qualified directors and executive officers.

The limitation of liability, indemnification and advancement provisions in our certificate of incorporation and bylaws may discourage stockholders from bringing a lawsuit against directors and officers for breach of their fiduciary duty. These provisions also may have the effect of reducing the likelihood of derivative litigation against directors and officers, even though such an action, if successful, might otherwise benefit us and our stockholders. In addition, your investment may be adversely affected to the extent we pay the costs of settlement and damage awards against directors and officers pursuant to these indemnification provisions.

There is currently no pending material litigation or proceeding involving any of our directors, officers or employees for which indemnification is sought.

Transfer Agent and Registrar

The transfer agent and registrar for shares of our Class A common stock and Class B common stock is Computershare Trust Company.

Listing

Our Class A common stock is listed on NYSE under the symbol "GRDN."

SELLING STOCKHOLDERS

Information regarding the identities of any selling stockholders, any material relationships the selling stockholders have had within the past three years with the Company, the beneficial ownership of our Class A common stock and Class B common stock by the selling stockholders, the number of shares of Class A common stock to be offered by the selling stockholders and the percentage to be owned by the selling stockholders after completion of the applicable offering will be set forth in a prospectus supplement, in a post-effective amendment, or in filings we make with the SEC under the Exchange Act which are incorporated by reference.

PLAN OF DISTRIBUTION

We and the selling stockholders may sell our Class A common stock in and outside the United States:

The distribution of our Class A common stock may be effected, from time to time, in one or more transactions, including:

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We and the selling stockholders may distribute our Class A common stock from time to time in one or more transactions at:

The prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of our Class A common stock, including the following:

If underwriters are used in the sale, the securities will be acquired by the underwriters for their own account and may be resold from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. Our Class A common stock may be either offered to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Unless we or the selling stockholders inform you otherwise in the applicable prospectus supplement, the obligations of the underwriters to purchase shares of our Class A common stock will be subject to conditions precedent and the underwriters will be obligated to purchase all of the offered Class A common stock if any are purchased. Any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.

If dealers are used in the sale, we or the selling stockholders will sell our Class A common stock to the dealers as principals. The dealers may resell the shares of our Class A common stock to the public at prices determined by the dealers at the time of the resale.

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We or the selling stockholders may sell our Class A common stock directly or through agents we designate from time to time. Any agent involved in the offer or sale of our Class A common stock in respect of which this prospectus is delivered will be named, and any commissions payable by us to that agent, will be described in the prospectus supplement.

The names of the underwriters, dealers or agents, as the case may be, and the terms of the transaction will be set forth in the applicable prospectus supplement.

Agents, dealers and underwriters may be entitled to indemnification by us or the selling stockholders against civil liabilities arising out of this prospectus, including liabilities under the Securities Act, or to contribution with respect to payments which the agents, dealers or underwriters may be required to make relating to those liabilities. Agents, dealers and underwriters may be customers of, engage in transactions with, or perform services for us in the ordinary course of business.

Our Class A common stock is listed on the NYSE. Any person participating in an offering of securities may make a market in such Class A common stock, but may discontinue such market-making at any time without notice. No assurances can be given that there will be a market for the shares of our Class A common stock.

Certain persons participating in an offering may engage in over-allotment, stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Exchange Act that stabilize, maintain or otherwise affect the price of the offered shares of our Class A common stock. If any such activities will occur, they will be described in the applicable prospectus supplement.

LEGAL MATTERS

The validity of the issuance of our Class A common stock offered hereby will be passed upon for us by Jones Day, Atlanta, Georgia. Additional legal matters may be passed upon for any underwriters, dealers or agents by counsel that will be named in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of Guardian Pharmacy Services, Inc. appearing in Guardian Pharmacy Services, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2024, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon included therein, and incorporated herein by reference. Such financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the report of Ernst & Young LLP pertaining to such financial statements (to the extent covered by consents filed with the Securities and Exchange Commission) given on the authority of such firm as experts in accounting and auditing.

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5,000,000 Shares

Class A Common Stock

P R O S P E C T U S  S U P P L E M E N T

    , 2026