It was proclaimed by the current Sultan of Perak, Sultan Nazrin Muizzuddin Shah on 11 January 2016 at the Tanjung Malim District Council Building. It had been part of Batang Padang district.
It will compromise an area of 93435 hectare land that includes the current sub-district of Tanjung Malim, located south in Batang Padang District. After proclamation, it will have three mukims, which is Slim, West Ulu Bernam and East Ulu Bernam.
The district will include towns in areas in Slim River and Tanjung Malim such as Tanjung Malim, Slim, and Proton City. It has been given the name Muallim, the Arabic word that means “teacher” because of the existence of Sultan Idris Education University in the proposed district’s area which has produced many teachers since the colonial era.