On May 8, 2026, Artiva Biotherapeutics, Inc. (the "Company") entered into an underwriting agreement (the "Underwriting Agreement") with Jefferies LLC, TD Securities (USA) LLC and Cantor Fitzgerald & Co., as representatives of the several underwriters listed therein (collectively, the "Underwriters"), to issue and sell 23,871,526 shares (the "Shares") of the Company's common stock, par value $0.0001 per share (the "Common Stock") at a price of $11.52 per share and pre-funded warrants (the "Pre-Funded Warrants") to purchase 2,170,138 shares of Common Stock at a price of $11.5199 per Pre-Funded Warrant, which represents the per share offering price for the Shares less the $0.0001 exercise price of each Pre-Funded Warrant (the "Offering"). The Offering was made pursuant to an effective registration statement on Form S-3 (File No. 333-289325) and related prospectus and prospectus supplement, in each case filed with the Securities and Exchange Commission (the "SEC"). All of the Shares and the Pre-Funded Warrants were sold by the Company.

The gross proceeds to the Company from the offering are expected to be approximately $300.0 million, before deducting the underwriting discount and commissions and estimated offering expenses payable by the Company. The closing of the offering is expected to occur on May 11, 2026, subject to the satisfaction of customary closing conditions.

The Pre-Funded Warrants are exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the warrant if the holder, together with its affiliates, would beneficially own more than 4.99% (or 9.99%) of the number of shares of Common Stock outstanding immediately after giving effect to such exercise. A holder of Pre-Funded Warrants may increase or decrease this percentage to a percentage not in excess of 19.99% by providing at least 61 days' prior notice to the Company.

The Underwriting Agreement contains customary representations, warranties, covenants and agreements by the Company, customary conditions to closing, indemnification obligations of the Company and the Underwriters (as applicable), including for liabilities under the Securities Act of 1933, as amended (the "Securities Act"), other obligations of the parties and termination provisions. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement and may be subject to limitations agreed upon by the contracting parties.

A copy of the Underwriting Agreement and the form of Pre-Funded Warrant are filed as Exhibits 1.1 and 4.1, respectively, and are incorporated herein by reference. The foregoing descriptions of the Underwriting Agreement and the Pre-Funded Warrants do not purport to be complete and are qualified in their entirety by reference to such exhibits. A copy of the opinion of Cooley LLP relating to the legality of the securities issued and sold in the Offering is filed herewith as Exhibit 5.1.