Enliven Therapeutics Inc. American Stock Offering Prospectus (Version as of June 12, 2026)

8,933,334 Shares of Common Stock Our common stock is listed on the Nasdaq Global Select Market under the symbol “ELVN.” The last reported sale price of our common stock on theNasdaq Global Select Market on June10, 2026 was $37.00 per share. There is no established public trading market for the pre-funded warrants, and wedo not expect a market to develop. In addition, we do not intend to list the pre-funded warrants on the Nasdaq Global Select Market or any other nationalsecurities exchange or nationally recognized trading system. Investing in our securities involves risks. Please read “Risk Factors” beginning on pageS-12 of this prospectussupplement, and under similar headings in the other documents that are filed after the date hereof and incorporatedby reference into this prospectus supplement and accompanying prospectus, to read about factors you should Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities orpassed upon the adequacy or accuracy of this prospectus supplement. Any representation to the contrary is a criminal offense. We have granted the underwriters an option for a period of 30 days to purchase up to an additional 1,600,000 shares of our common stock at the publicoffering price less underwriting discounts and commissions. TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTMARKET, INDUSTRY, AND OTHER DATASPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSPROSPECTUS SUPPLEMENT SUMMARYTHE OFFERINGRISK FACTORSDESCRIPTION OFPRE-FUNDEDWARRANTSUSE OF PROCEEDSDIVIDEND POLICYDILUTIONMATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCESUNDERWRITINGLEGAL MATTERSEXPERTSWHERE YOU CAN FIND MORE INFORMATIONINCORPORATION OF CERTAIN INFORMATION BY REFERENCE Prospectus PAGEii1567 ABOUT THIS PROSPECTUSPROSPECTUS SUMMARYRISK FACTORSFORWARD-LOOKING STATEMENTSUSE OF PROCEEDSDESCRIPTION OF CAPITAL STOCKDESCRIPTION OF DEBT SECURITIES DESCRIPTION OF DEPOSITARY SHARES DESCRIPTION OF PURCHASE CONTRACTS WHERE YOU CAN FIND MORE INFORMATION ABOUT THIS PROSPECTUS SUPPLEMENT This document is in two parts. Thefirst part is this prospectus supplement, which describes the specific terms of this offering of common stock andpre-funded warrants and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by referenceinto this prospectus supplement and the accompanying prospectus. The second part is the accompanying prospectus, which gives more generalinformation, some of which may not apply to this offering. Generally, when we refer to this prospectus, we are referring to both the prospectussupplement and the accompanying prospectus. In this prospectus supplement, as permitted by law, we “incorporate by reference” information from otherdocuments that wefile with the Securities and Exchange Commission (the “SEC”). This means that we can disclose important information to you fromthose documents which we mayfile with the SEC from time to time. The information incorporated by reference is considered to be a part of thisprospectus supplement and the accompanying prospectus and should be read with the same care. This prospectus supplement describes the specific You should not consider any information in this prospectus supplement or the accompanying prospectus to be investment, legal, or tax advice. You shouldconsult your own counsel, accountants, and other advisers for legal, tax, business,financial, and related advice regarding the purchase of the commonstock and pre-funded warrants offered by this prospectus supplement. If the description of the offering varies between this prospectus supplement and This prospectus supplement and the accompanying prospectus are part of an automatic “shelf” registration statement that wefiled with the SEC as a“well-known seasoned issuer” as defined under the Securities Act. Under the shelf registration process, we may offer from time to time various securities,of which this offering of shares of our common stock and pre-funded warrants is a part. Such registration statement also includes exhibits that providemore detail on the matters discussed in this prospectus supplement and the accompanying prospectus. You should read this prospectus supplement, the Neither we nor the underwriters have authorized anyone to provide any information other than that contained or incorporated by reference in thisprospectus supplement, the accompanying prospectus or in any free writing prospectus prepared by or on behalf of us or to which we have referred you.We and the underwriters take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you.This prospectus supplement and the accompanying prospectus do not constitute an offer to sell, or a solicitation of an offer to purchase, the securitiesoffered by this prospectus supplement and the accompanying prospectus in any jurisdiction to or from an