Material Agreement (Form 8-K)

Item 1.01 Entry into a Material Definitive Agreement.

As previously disclosed, on May 1, 2026, FibroBiologics, Inc. (the "Company") entered into that certain At The Market Offering Agreement (the "Sales Agreement") with H.C. Wainwright & Co., LLC (the "Sales Agent") under which the Company may issue and sell shares of its common stock, par value $0.00001 per share (the "Common Stock") from time to time through or to the Sales Agent (the "ATM Offering"). The shares of Common Stock to be sold under the Sales Agreement, if any, will be issued and sold pursuant to the Company's shelf registration statement on Form S-3 (Registration No. 333-284663), which was filed with the Securities and Exchange Commission (the "SEC") on February 3, 2025, and declared effective by the SEC on February 10, 2025, including the base prospectus contained therein, a prospectus supplement which was filed with the SEC on May 1, 2026, and the Updated ATM Prospectus Supplement (as defined below).

On May 5, 2026, the Company filed a prospectus supplement to increase the maximum number of shares of Common Stock issuable pursuant to the ATM Offering to up to an aggregate offering price of up to $7,500,000 (the "Updated ATM Prospectus Supplement"). To date, 71,830 shares of Common Stock have been sold under the Sales Agreement.

In connection with the filing of the Updated ATM Prospectus Supplement, the Company is filing the opinion and consent of its counsel, Sichenzia Ross Ference Carmel LLP, regarding the validity of the shares of Common Stock that may be sold pursuant to the Sales Agreement as Exhibits 5.1 and 23.1, respectively, to this Current Report on Form 8-K, which are incorporated herein by reference.

This Current Report on Form 8-K shall not constitute an offer to sell or the solicitation of an offer to buy any shares of Common Stock, nor shall there be any sale of shares of Common Stock in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or other jurisdiction.

Item 9.01 Financial Statements and Exhibits.