6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the Month of December 2025

Commission File Number: 001-41621

RADIOPHARM THERANOSTICS LIMITED

(Name of Registrant)

Level 3, 62 Lygon Street, Carlton South, Victoria,3053, Australia

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☒       Form 40-F ☐

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes ☐       No ☒

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-

RADIOPHARM THERANOSTICS LIMITED

EXPLANATORY NOTE

Radiopharm Theranostics Limited (the “Company”) published an announcement (the “Public Notice”) to the Australian Securities Exchange on December 3, 2025 titled:

“Results of Meeting”

A copy of the Public Notice is attached as an exhibit to this report on Form 6-K.

This report on Form 6-K (including the exhibit hereto) shall not be deemed to be “filed” for purposes of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and shall not be incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

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EXHIBITS

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SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

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Exhibit 99.1

Results of General Meeting

Sydney, Australia – Wednesday, 3 December 2025 – Radiopharm Theranostics Limited (ASX: RAD; Nasdaq: RADX) advises that all resolutions considered at the General Meeting held today were carried by poll.

In accordance with ASX Listing Rule 3.13.2 and Section 251AA(1) of the Corporations Act 2001, details of the proxies received and votes cast in respect of each resolution are attached.

Phillip Hains

Joint Company Secretary

Radiopharm Theranostics Limited

Suite 1, Level 3, 62 Lygon Street,Carlton South VIC 3053 Australia

ABN: 57 647 877 889

Disclosure of Proxy Votes
Radiopharm Theranostics Limited<br><br> Extraordinary<br> General Meeting<br><br> Wednesday, 03 December 2025	GPO Box 5193, Sydney, NSW<br>2001<br><br>P 1300 288 664 (aus) or +61 (0)2 9698 5414 (world)<br><br>F +61 (0)2 8583 3040 E [email protected]<br><br>ABN 27 152 260 814

In accordance with section 251AA of the Corporations Act 2001, the following information is provided in relation to resolutions put to members at the meeting.