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 March 2025

Commission File Number: 001-15092

TURKCELL ILETISIM HIZMETLERI A.S.

(Translation of registrant’s name into English)

Aydınevler Mahallesi İnönü Caddesi No:20

Küçükyalı Ofispark

34854 Maltepe
Istanbul, Türkiye

(Address of Principal Executive Offices)

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

x Form 20-F  ¨ Form 40-F

Enclosure: A press release dated March 25, 2025, announcing the registrant’s board of directors’ resolution on buy-back of securities.

Istanbul, March 25, 2025

Announcement Regarding the Board of Directors Resolution on Buy-Back of Securities

Our Company's Board of Directors resolved to increase the maximum fund amount for the buyback of Company’s shares, trading on Borsa İstanbul A.Ş., American Depository Receipts (ADRs) trading on the New York Stock Exchange (NYSE), and the Company's bonds from TRY 1,250,000,000 to TRY 2,250,000,000, pursuant to the relevant legislation and regulations of the Capital Markets Board.

For more information:

Turkcell Investor Relations

investor.relations@turkcell.com.tr

Tel: + 90 212 313 1888

SIGNATURES

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