Exhibit 5.1

1271 Avenue of the Americas | New York, New York 10020 Blankrome.com

March 25, 2026

Immix Biopharma, Inc.

11400 West Olympic Blvd., Suite 200

Los Angeles, California 90064

Re: Immix Biopharma, Inc. – Securities Registered Under the Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to Immix Biopharma, Inc., a Delaware corporation (the “Company”), in connection with the offering by the Company of shares of its common stock, par value $0.0001 per share (“Common Stock”), having an aggregate offering price of up to $100,000,000 (the “Shares”) pursuant to the Registration Statement on Form S-3 (File No. 333-292665) (the “Registration Statement”) filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), the prospectus included in the Registration Statement (the “Base Prospectus”) and the prospectus supplement dated March 25, 2026, filed with the Commission pursuant to Rule 424(b)(5) promulgated under the Securities Act (together with the Base Prospectus, the “Prospectus”). The Shares are to be sold (if any) by the Company under that certain At The Market Offering Agreement, dated June 3, 2025, as amended, entered into by and between the Company and Citizens JMP Securities, LLC (the “Sales Agreement”), as described in the Prospectus.

In rendering the opinions set forth herein, we have examined originals or copies, certified or otherwise identified to our satisfaction, of (i) the Registration Statement, (ii) the Prospectus, (iii) the Sales Agreement, (iv) resolutions adopted by the Board of Directors of the Company (the “Board”), (v) the Third Amended and Restated Certificate of Incorporation of the Company, (vi) the Amended and Restated Bylaws of the Company, and (vii) such other corporate records, agreements, certificates, including, but not limited to, certificates or comparable documents of public officials and of officers and representatives of the Company, statutes and other instruments and documents as we considered relevant and necessary as a basis for the opinions hereinafter expressed.

In rendering this opinion, we have assumed, without inquiry, (i) the authenticity of all documents submitted to us as originals; (ii) the conformity to the original documents of all documents submitted to us as facsimile, electronic, certified or photostatic copies, and the authenticity of the originals of such copies; (iii) the legal capacity of all natural persons and the genuineness of all signatures on the Registration Statement and all documents submitted to us; and (iv) that the books and records of the Company are maintained in accordance with proper corporate procedures.

March 25, 2026

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In connection with the Shares, we have assumed (i) that each sale of Shares will be duly authorized by the Board, a duly authorized committee thereof or a person or body pursuant to an authorization granted in accordance with Section 152 of the Delaware General Corporation Law (the “DGCL”), (ii) that the price at which the Shares are sold will equal or exceed the par value of the Common Stock, and (iii) at the time of issuance of any Shares, there shall be a sufficient number of duly authorized and unissued shares of Common Stock to accommodate the issuance of the Shares. We express no opinion to the extent that future issuances of securities of the Company, anti-dilution adjustments to outstanding securities of the Company and/or other matters cause the number of shares of the Common Stock available for issuance under the Sales Agreement to exceed the number of shares of the Common Stock available for issuance by the Company.

Our opinion herein is expressed solely with respect to the DGCL. Our opinion is based on these laws as in effect on the date hereof. We express no opinion to the extent that any other laws are applicable to the subject matter hereof and express no opinion and provide no assurance as to compliance with any federal or state securities law, rule or regulation.

Based on the foregoing, and subject to the qualifications, exceptions and assumptions stated herein, we are of the opinion that when the Shares have been issued and paid for in accordance with the terms and conditions of the Sales Agreement and as provided in the Registration Statement and the Prospectus, the Shares will be validly issued, fully paid and nonassessable.

We hereby consent to the reference to our firm under the caption “Legal Matters” in the Prospectus and to the filing of this opinion as an exhibit in the Current Report on Form 8-K to be filed with the Commission for incorporation by reference into the Registration Statement. In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder.

This opinion is strictly limited to the matters stated herein and no other or more extensive opinion is intended, implied or to be inferred beyond the matters expressly stated herein. This opinion letter is not a guaranty nor may one be inferred or implied. This opinion speaks only as to law and facts in effect or existing as of the date hereof, and we have no obligation or responsibility to update or supplement this opinion to reflect any facts or circumstances that may hereafter come to our attention or any changes in law that may hereafter occur.

Exhibit 10.2

March 25, 2026

Immix Biopharma, Inc.

11400 West Olympic Blvd., Suite 200

Los Angeles, CA 90064

Attention: Ilya Rachman, Chief Executive Officer and Chief Scientific Officer

Dear Mr. Rachman:

Reference is made to the At The Market Offering Agreement, dated as of June 3, 2025 (the “ATM Agreement”), between Immix Biopharma, Inc., a corporation organized under the laws of Delaware (the “Company”) and Citizens JMP Securities, LLC (the “Manager”). This letter (the “Amendment”) constitutes an agreement between the Company and the Manager to amend the ATM Agreement as set forth herein. Defined terms that are used but not defined herein shall have the meanings ascribed to such terms in the ATM Agreement.

1. The defined term “Agreement” in the ATM Agreement is amended to mean the ATM Agreement as amended by this Amendment.

2. The subtitle on the first page of the ATM Agreement stating “Up to $50,000,000 Shares of Common Stock” is hereby deleted in its entirety and shall have no further force or effect. All references in the ATM Agreement shall be read without giving effect to such subtitle.

3. The definition of “Registration Statement” is hereby amended and restated as follows:

““Registration Statement” shall mean the shelf registration statement (File Number 333-292665) on Form S-3, including exhibits and financial statements and any prospectus supplement relating to the Shares that is filed with the Commission pursuant to Rule 424(b) and deemed part of such registration statement pursuant to Rule 430B, as amended on each Effective Date and, in the event any post-effective amendment thereto becomes effective, shall also mean such registration statement as so amended.”

4. Section 2 of the ATM Agreement is hereby amended and restated as follows:

“The Company proposes to issue and sell through or to the Manager, as sales agent and/or principal, from time to time during the term of this Agreement and on the terms set forth herein, up to such number of shares (the “Shares”) of the Company’s common stock, $0.0001 par value per share (“Common Stock”), that does not exceed (a) the number or dollar amount of shares of Common Stock registered on the Registration Statement and as reflected on the Prospectus Supplement, pursuant to which the offering is being made, (b) the number of authorized but unissued shares of Common Stock (less the number of shares of Common Stock issuable upon exercise, conversion or exchange of any outstanding securities of the Company or otherwise reserved from the Company’s authorized capital stock), or (c) the number or dollar amount of shares of Common Stock that would cause the Company or the offering of the Shares to not satisfy the eligibility and transaction requirements for use of Form S-3, including, if applicable, General Instruction I.B.6 of Registration Statement on Form S-3 (the lesser of (a), (b) and (c), the “Maximum Amount”). Notwithstanding anything to the contrary contained herein, the parties hereto agree that compliance with the limitations set forth in this Section 2 on the number and aggregate sales price of Shares issued and sold under this Agreement shall be the sole responsibility of the Company and that the Manager shall have no obligation in connection with such compliance.”

5. Section 4(h) of the ATM Agreement is hereby amended and restated as follows:

“(h) Subsequent Equity Issuances. The Company shall not (i) deliver any Sales Notice hereunder (and any Sales Notice previously delivered shall not apply during such one (1 Trading Day) for at least one (1) Trading Day prior to any date on which the Company or any Subsidiary offers, sells, issues, contracts to sell, contracts to issue or otherwise disposes of, directly or indirectly, any other shares of Common Stock or any Common Stock Equivalents (other than the Shares), subject to Manager’s right to waive this obligation, provided that, without compliance with the foregoing obligation, the Company may issue and sell Common Stock pursuant to any employee equity plan, stock ownership plan or dividend reinvestment plan of the Company in effect at the Execution Time, and the Company may issue Common Stock issuable upon the conversion or exercise of Common Stock Equivalents outstanding at the Execution Time.”

6. Except as expressly set forth herein, all of the terms and conditions of the ATM Agreement shall continue in full force and effect after the execution of this Amendment and shall not be in any way changed, modified or superseded by the terms set forth herein.

7. This Amendment may be executed in two or more counterparts and by facsimile or “.pdf” signature or otherwise, and each of such counterparts shall be deemed an original and all of such counterparts together shall constitute one and the same agreement.

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In acknowledgment that the foregoing correctly sets forth the understanding reached by the Company and the Manager, please sign in the space provided below, whereupon this Amendment shall constitute a binding amendment to the ATM Agreement as of the date indicated above.

[signature page to IMMX Amendment to

atm agreement]