The Mountain Empire is a rural area in southeastern San Diego County, California.

[1] The Mountain Empire subregion consists of the backcountry communities in southeastern San Diego County.

Portions of the Mountain Empire are located in the Descanso Ranger District of the Cleveland National Forest.

Historic U.S. Route 80 also passes through the Mountain Empire, as does the now disused San Diego and Arizona Eastern Railway.

They include (populations as of 2020 census): The San Diego County Sheriff's Office provides patrol and law enforcement services to the Mountain Empire region.