Form 6-K CGI INC For: Dec 18

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 December 2025

Commission File Number 000-29716

CGI INC.

(Translation of registrant’s name into English)

1350 René-Lévesque Boulevard West

25th Floor

Montreal, Quebec

Canada H3G 1T4

(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 ☒

INCORPORATION BY REFERENCE

Exhibits 99.1, 99.2, 99.3 and 99.4 to this Form 6-K shall be deemed incorporated by reference in the Registrant’s Registration Statement on Form F-10, Reg. No. 333-292245.

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.