Immix Biopharma Inc. American Depositary Share Prospectus (Version as of May 21, 2026)

Immix Biopharma, Inc. We are offering 16,778,524 shares of our common stock in this offering. Our common stock is listed on the Nasdaq Capital Market and traded under the symbol “IMMX.” On May 20, 2026, theclosing price of our common stock, as reported on Nasdaq was $8.94 per share. We are an “emerging growth company” as defined in Section 2(a) of the Securities Act of 1933, as amended (the “SecuritiesAct”) and we have elected to comply with certain reduced public company reporting requirements. You should read this prospectus supplement and the accompanying prospectus, together with additional informationdescribed under the headings “Incorporation of Certain Documents by Reference” and “Where You Can Find More Information,” carefully before you invest in any of our securities. Investing in our securities involves a high degree of risk. You should carefully review and consider the “Risk Factors’’section beginning on page S-6 of this prospectus supplement and page 5 of the accompanying prospectus and in the documents (1)See the section titled “Underwriters” beginning on page S-18 of this prospectus supplement for a description of the compensationpayable to the underwriters. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved ofthese securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Anyrepresentation to the contrary is a criminal offense. The underwriters expect to deliver the shares of common stock to purchasers against payment on or about May 22, 2026. Morgan Stanley Co-Lead Managers LifeSci Capital TABLE OF CONTENTS Prospectus ABOUT THIS PROSPECTUS This prospectus supplement and the accompanying prospectus are part of a registration statement on Form S-3 (File No. 333-292665) that we filed with the Securities and Exchange Commission (the “SEC”) on January 9, 2026, and that was declared effectiveby the SEC on January 22, 2026 using a “shelf” registration process. This document is in two parts. The first part is this prospectussupplement, which describes the specific terms of this offering and also adds to and updates information contained in theaccompanying prospectus and the documents incorporated by reference herein. The second part, the accompanying prospectus,provides more general information, some of which may not apply to this offering. Generally, when we refer to this prospectus, we arereferring to both parts of this document combined. To the extent there is a conflict between the information contained in this We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit toany document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, insome cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, We have not authorized, and the underwriters have not authorized, anyone to provide you with information that is in additionto or different from that contained or incorporated by reference in this prospectus supplement, the accompanying prospectus, or anyfree writing prospectus provided in connection with this offering. Neither we nor the underwriters take any responsibility for, andneither we nor the underwriters provide any assurance as to the reliability of, any other information that others may give you. Youshould not assume that the information contained or incorporated by reference in this prospectus supplement, the accompanyingprospectus, or any free writing prospectus provided in connection with this offering is accurate as of any date other than as of the date This prospectus supplement and the accompanying prospectus and any issuer free writing prospectus relating to this offeringcontain summaries of certain provisions contained in some of the documents described herein, but reference is made to the actualdocuments for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of It is important for you to read and consider all information contained in this prospectus supplement and the accompanyingprospectus and in any issuer free writing prospectus relating to this offering, including the documents incorporated by reference hereinand therein, in making your investment decision. You should also read and consider the information in the documents to which we This prospectus supplement and the accompanying prospectus contain and incorporate by reference market data and industrystatistics and forecasts that are based on independent industry publications and other publicly-available information. Although webelieve these sources are reliable, we do not guarantee the accuracy or completeness of this information and we have notindependently verified this information. Although we are not aware of any misstatements