6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report ofForeign Private Issuer

Pursuant to Rule 13a-16 or15d-16

under the Securities Exchange Act of 1934

Date of Report: December 7, 2021

Commission File Number: 001-36891

Cellectis S.A.

(ExactName of registrant as specified in its charter)

8, rue de laCroix Jarry

75013 Paris, France

+33 1 81 69 16 00

(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 if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

This report on Form 6-K shall be deemed to be incorporated by reference in the registration statements of Cellectis S.A. on Form F-3 (No. 333-238881) and Form S-8 (Nos. 333-204205, 333-214884, 333-222482 and 333-227717), to the extent not superseded by documents or reports subsequently filed.

Management Update

Cellectis S.A. (the “Company”) previously announced that Eric Dutang would leave his position as the Company’s Chief Financial Officer (“CFO”) to pursue new opportunities. Mr. Dutang’s departure date was accelerated and became effective as of December 2, 2021.

As previously reported, the Company has initiated a search to identify a new Chief Financial Officer. Valérie Cros, Senior Director, Accounting and Internal Controls, is acting as the Company’s principal financial officer and principal accounting officer until a successor CFO is named.

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.