The Ottoman Caliphate, the world's last widely recognized caliphate, was abolished on 3 March 1924 by decree of the Grand National Assembly of Turkey. The process was one of Atatürk's reforms following the replacement of the Ottoman Empire with the Republic of Turkey. Abdulmejid II was deposed as the last Ottoman caliph, as was Mustafa Sabri as the last Ottoman Shaykh al-Islām.

The caliphate of the Ottoman Empire was the claim of the heads of the Turkish Ottoman dynasty to be the caliphs of Islam in the late medieval and early modern era. During the period of Ottoman expansion, Ottoman rulers claimed caliphal authority after the conquest of Mamluk Egypt by sultan Selim I in 1517 and the abolition of the Mamluk-controlled Abbasid Caliphate. This left Selim as the Defender of the Holy Cities of Mecca and Medina and strengthened the Ottoman claim to leadership in the Muslim world.