The Central Mindanao Region was created on July 7, 1975 under P.D. No. 742. Under this decree, Central Mindanao was then composed of the provinces of Cotabato, Sultan Kudarat, Lanao del Norte, Lanao del Sur, and Maguindanao, and the cities of Iligan, Cotabato and Marawi. The extent of regionalization was further seen in the establishment of Autonomous Region in Central and Western Mindanao (Region XII and IX) by virtue of P.D. No. 1618.
On August 1, 1989, RA No. 6734 was signed into law and provided for the creation of the Autonomous Region in Muslim Mindanao (ARMM), the composition of which include Lanao del Sur and Maguindanao provinces. The former Regional Autonomous Government of Central Mindanao was therefore reverted to an administrative region. EO 429 was issued on October 12, 1990 defining the new composition of Central Mindanao with Koronadal City as its Regional Administrative Center. However, a restraining order was issued against the implementation of the executive order. Thus the original composition of Region XII prior to the issuance of EO 429 (e.i. Cotabato Province, Sultan Kudarat, Lanao del Norte,Cotabato City, Iligan City and Marawi City) remained status quo. Cotabato City remained as Regional Administrative Center for Region XII. It has been likewise designated as the temporary regional center of ARMM.
On February 23, 1995, RA 7901, “ An act creating Region XIII to be known as the Caraga Administrative Region and for other purposes” was enacted. Section 3 of the said law provided for the transfer of Sultan Kudarat to Region XI following Surigao del Sur’s transfer from Region XI to the Caraga Region. However, in 1998, RA 8744 was passed transferring back to Region XII the province of Sultan Kudarat.
Pursuant to the provisions of the Final Peace Agreement signed between the Government of the Republic of the Philippines and the Moro National Liberation Front (MNLF) on September 6, 1996, EO No. 371 was issued by His Excellency Fidel V. Ramos on October 2, 1996 which established a Special Zone of Peace and Development(SZOPAD) in Southern Philippines encompassing five regions, including Region XII.
On August 14, 2001, a plebiscite was conducted in the SZOPAD to determine the areas that shall comprise the ARMM, pursuant to RA No. 9054. The cities of Marawi in Region XII and Isabela in Region IX joined the ARMM. As a result, an administrative measure following the reconfiguration of ARMM, President Gloria Macapag Arroyo issued EO No. 36 dated September 19, 2001, which realigned the regions in Mindanao. The province of Lanao del Norte and Iligan City of Region XII was transferred to Region X. The provinces of South Cotabato, Sarangani and the cities of Koronadal and General Santos of Region XI became part of the new Region XII.