The Mahdist War (1881–99) was a war of the late 19th century between the Mahdist Sudanese of the religious leader Muhammad Ahmad bin Abd Allah, who had proclaimed himself the "Mahdi" of Islam (the "Guided One"), and the forces of the Khedivate of Egypt (an autonomous tributary state of the Ottoman Empire, established and ruled by the Muhammad Ali Dynasty), initially, and later the forces of Britain. Eighteen years of war resulted in the nominally joint-rule state of the Anglo-Egyptian Sudan (1899–1956), a part of the British Empire and the Kingdom of Egypt in which Britain had control over the Sudan. The Sudanese launched several unsuccessful invasions of their neighbor, expanding the scale of the conflict to include not only Britain and Egypt but the Italian Empire, the Belgian Congo and the Ethiopian Empire.

The British participation in the war is called the Sudan Campaign. Other names for this war includes the "Mahdist Revolt", the "Anglo–Sudan War" and the "Sudanese Mahdist Revolt".