UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 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 May 2025

Commission File Number: 001-41709

 SEALSQ CORP

(Exact Name of Registrant as Specified in Charter)

N/A

(Translation of 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

This Form 6-K is hereby incorporated by reference into the registration statement on Form F-3 of the Company (File No. 333- 286098) and into the base prospectus and any prospectus supplement outstanding under the foregoing registration statement, to the extent not superseded by documents or reports subsequently filed or furnished by the Company under the Securities Act, or the Exchange Act.

Exhibit Index

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.