The caliphate of the Ottoman Empire (Ottoman Turkish: خلافت مقامى, romanized: hilâfet makamı, lit. 'office of the caliphate') was the claim of the heads of the Turkish Ottoman dynasty to be the caliphs of Islam in the late medieval and the 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, which bestowed the title of Defender of the Holy Cities of Mecca and Medina upon him and strengthened the Ottoman claim to caliphate in the Muslim world.

The demise of the Ottoman Caliphate took place because of a slow erosion of power in relation to Western Europe, and because of the end of the Ottoman state as a consequence of the partitioning of the Ottoman Empire by the League of Nations mandate. Abdulmejid II, the last Ottoman caliph, held his caliphal position for a couple of years after the partitioning, but with Mustafa Kemal Pasha's secular reforms and the subsequent exile of the imperial Osmanoğlu family from Turkey in 1924, the caliphal position was abolished. Mustafa Kemal Pasha offered the caliphate to Ahmed Sharif as-Senussi, on the condition that he reside outside Turkey; Senussi declined the offer and confirmed his support for Abdulmejid II.

With the establishments of Bektashi and Mevlevi orders, heterodox, syncretic and mystic approaches to Islam like Sufism flourished.