The district Mueang Chaem was created in 1908, consisting of the tambon Mae Thap,Tha Pha, Chang Khoeng and Mae Suek split off from Chom Thong. In 1917 it was renamed to Chang Khoeng, as the district office was located in that tambon. In 1938 it was reduced to a minor district and was a subordinate of Chom Thong district. 1939 it was renamed to Mae Chaem. In 1956 it was upgraded to a full district. In 2009 the northern part of the district was split off to form the new district Galyani Vadhana.
Neighboring districts are (from the east clockwise) Samoeng, Mae Wang, Chom Thong and Hot of Chiang Mai Province, and Mae Sariang, Mae La Noi, Khun Yuam, Mueang Mae Hong Son and Pai of Mae Hong Son Province.