Feridun Hadi Sinirlioğlu (born 30 January 1956) is a Turkish diplomat and politician serving as the Secretary General of the Organization for Security and Co-operation in Europe (OSCE) since 6 December 2024.

Returning to Ankara, between 1991 and 1992 he worked as First Secretary at the Bilateral Political Department in charge of Greece, as Special Advisor to the Deputy Undersecretary for Bilateral Political Affairs, as Special Advisor to the Undersecretary and then as Speechwriter to the Prime Minister.

After serving the President for four years, in 2000 he became Deputy Director General for the Middle East and North Africa.

Sinirlioğlu served as the Minister of Foreign Affairs for the interim government between 28 August 2015 and 24 November 2015.

He was then reappointed as Undersecretary and served in that capacity until October 2016, when he assumed his position as the Permanent Representative of the Republic of Turkey to the United Nations.