6-K

UNITED STATES

SECURITIES AND EXCHANGECOMMISSION

WASHINGTON, DC 20549

FORM 6-K

Report of Foreign PrivateIssuer

Pursuant to Rule 13a-16 or 15d-16 under the

Securities Exchange Act of 1934

For the month of November 2025

Commission File Number: 001-41709

SEALSQCORP

(Exact Name ofRegistrant as Specified in Charter)

N/A

(Translationof Registrant’s name into English)

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

Dr. Hossein Rahnama resigned from SEALSQ Corp’s (the “Company”) board of directors (the “Board”) effective October 28, 2025. Dr. Rahnama’s resignation did not result from any disagreement with the Board or the Company.

The Board is not considering appointing another independent director until the Company’s next annual general meeting.

The information contained in this Report on Form 6-K is hereby incorporated by reference into the registration statement on Form F-3 of the Company (File No. 333-290963), as amended, and the registration statement on Form S-8 of the Company (File No. 333-287139), and into the base prospectus and any prospectus supplement outstanding under each of the foregoing registration statements, to the extent not superseded by documents or reports subsequently filed or furnished by the Company under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934.

SIGNATURES

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.