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 April 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 April 29, 2025, announcing the registrant's application to the Capital Markets Board for approval of a debt instrument issuance certificate.

Istanbul, April 29, 2025

Announcement Regarding the Application to the Capital Markets Board for a Debt Instrument Issuance in the Domestic Market

With reference to our Company’s announcement dated March 26, 2025, we made an application to the Capital Markets Board for the approval of a debt instrument issuance certificate.

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.