Francisco de Atienza and Portuguese Recollect Friar Agustin de San Pedro were the first to set foot on Lanao soil, reaching the lake region on April 4, 1639.

The conquest of Lanao, however, started two years earlier, when Governor General Hurtado de Corcuera captured Lamitan on the coast of Mindanao in 1637. In 1639, General Pedro Almonte marched towards the interior regional, near Lake Lanao, and captured the Marawi fortress after heavy fighting. Until the end of the Spanish rule, Lanao del Sur constituted several Muslim areas each ruled by a datu.

In 1895, Lanao was made a politico military government, as the 7th district of Mindanao and Sulu. In 1914, the Americans established a civil government under the Department of Mindanao and Sulu, and Lanao became one of the seven provinces of the department.

Lanao del Sur achieved its status as an independent province on May 22,1959 when Republic Act No. 2228 divided Lanao into two provinces.