Bull Lake is an unincorporated community and census-designated place (CDP) in Lincoln County, Montana, United States. As of the 2020 census, Bull Lake had a population of 180. It is in the southwestern part of the county, surrounding the lake of the same name. Montana Highway 56 runs along the east side of the lake, leading north to Troy in the Kootenay River valley and south to Montana Highway 200 in the Clark Fork valley.
Bull Lake was first listed as a CDP prior to the 2020 census.