SOLIGENIX, INC.

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SOLIGENIX, INC.

29 Emmons Drive, Suite B-10

Princeton, New Jersey 08540

Annual Meeting of Stockholders

Thursday, September 17, 2026

This Proxy Statement has been prepared and is distributed by the board of directors (the “Board of Directors”) of Soligenix, Inc. in connection with the solicitation of proxies for the Annual Meeting of Stockholders (the “Annual Meeting”) to be held at 9:00 a.m., Eastern Daylight Time, on Thursday, September 17, 2026, and any adjournment or postponement thereof for the purposes set forth in the accompanying Notice of Annual Meeting of Stockholders. The Annual Meeting will be a completely “virtual meeting” of stockholders. You will be able to attend the Annual Meeting as well as vote and submit your questions during the live webcast of the meeting by visitingwww.virtualshareholdermeeting.com/sngx2026 and entering the 16-digit control number included on your proxy card or on the instructions that accompanied your proxy materials. Unless the context indicates otherwise, as used in this Proxy Statement, the terms “we,” “us” “our” and “our Company” refer to Soligenix, Inc.

This Proxy Statement and the accompanying form of proxy will be made available to stockholders on or about August 3, 2026. Our Annual Report on Form 10-K for the year ended December 31, 2025 (which does not form a part of the proxy solicitation materials) is being distributed concurrently herewith to stockholders.

Voting Securities; Voting Your Shares; Proxies; Required Vote

VOTING SECURITIES

Each holder of record of our common stock, par value $0.001 per share (“Common Stock”), at the close of business on July 20, 2026 will be entitled to one vote for each share of Common Stock owned on that date as to each matter presented at the Annual Meeting. On July 20, 2026, 21,765,479 shares of Common Stock were outstanding.

VOTING YOUR SHARES

The Annual Meeting will be held entirely online. Stockholders may participate in the Annual Meeting by visiting the following website: www.virtualshareholdermeeting.com/sngx2026. To participate in the Annual Meeting, you will need the 16-digit control number included on your proxy card or on the instructions that accompanied your proxy materials. Shares held in your name as the stockholder of record may be voted electronically during the Annual Meeting. Shares for which you are the beneficial owner but not the stockholder of record also may be voted electronically during the Annual Meeting. However, even if you plan to participate in the Annual Meeting, we recommend that you vote your shares in advance, so that your vote will be counted if you later decide not to attend the Annual Meeting. You may vote your shares via the Internet, telephone or mail as more fully described below:

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By Internet: Go towww.proxyvote.com and follow the instructions (have your proxy card available);

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By Telephone: Call 1-800-690-6903 and follow the voice prompts (have your proxy card available); and

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By Mail: If you have received a proxy card, mark your vote, sign your name exactly as it appears on your proxy card, date your card and return it in the envelope provided.

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PROXIES

You cannot vote your shares at the meeting unless you vote electronically or are represented by proxy. All properly executed and unrevoked proxies that are received in time for the meeting will be voted at the meeting or any adjournment or postponement thereof in accordance with instructions thereon, or if no instructions are given, will be voted as follows:

“FOR ALL” in the election of all of the named nominees as directors;

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“FOR” the approval of the Reverse Stock Split Proposal;

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“FOR” the approval of the Authorized Shares Proposal;

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“FOR” the approval, on an advisory basis, of the compensation of our executive officers;

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“ONE YEAR” for the approval, on an advisory basis, of the frequency with which stockholders are provided an advisory vote on executive compensation;

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“FOR” the ratification of Cherry Bekaert LLP as our independent registered public accounting firm for the year ending December 31, 2026;

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“FOR” the approval of the Adjournment Proposal; and

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In accordance with the judgment of the persons appointed as proxies with respect to other matters which properly come before the Annual Meeting.

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Stockholders of record may revoke their proxy at any time before the electronic polls close by submitting a later-dated vote online during the Annual Meeting, via the Internet, by telephone, or by mail, or by delivering written instructions to our Corporate Secretary before the Annual Meeting commences. Beneficial stockholders may revoke any prior voting instructions by contacting brokers, banks, or other nominees (“Brokers”) that hold their shares or by voting online during the meeting.

REQUIRED VOTE

The following table summarizes the vote required for each proposal, the classification of each proposal as routine or non-routine, and the effect of abstentions and Broker non-votes on each proposal:

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As Proposals 2, 3, 6 and 7 are considered “routine” matters, we do not expect that any Broker non-votes will be recorded for such proposals; however, Broker non-votes may still occur if Brokers choose not to exercise their discretionary authority on a routine matter due to internal policies or otherwise.

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Brokers who hold shares on behalf of beneficial stockholders have discretion to vote such shares with respect to “routine” matters without receiving voting instructions from the beneficial holders of the shares; however, Brokers may choose not to exercise their discretionary authority due to internal policies or otherwise. Brokers do not have discretion to vote such shares with respect to “non-routine” matters without receiving voting instructions. If no instruction is given to Brokers with respect to “non-routine” matters, a “Broker non-vote” is recorded for each such uninstructed share.

Stockholders are not allowed to cumulate their votes in the election of directors.

QUORUM

The required quorum for the transaction of business at the Annual Meeting is one-third of the voting power of shares of Common Stock issued and outstanding on the record date. Shares represented in person or by proxy (including shares which abstain or do not vote with respect to one or more of the matters presented for stockholder approval) will be counted for purposes of determining whether a quorum exists at the meeting.

No Appraisal Rights

Stockholders will not have any appraisal rights in connection with any of the proposals to be voted on at the Annual Meeting.