The Autonomous Region in Muslim Mindanao (ARMM) of the Philippines is composed of five provinces and one city namely: Basilan, Lanao del Sur, Maguindanao, Sulu, Tawi-Tawi and the Marawi City. Executive Order No. 36 moved Basilan from Region IX and Marawi City from Region XII. Cotabato City is the seat of the regional government, but the city itself is part of Region XII.

The region was first created on August 1, 1989 through Republic Act No. 6734 otherwise known as the Organic Act. ARMM was officially inaugurated on November 6, 1990 in Cotabato City.