Broadwater County is centrally located in southwestern Montana. It borders Lewis and Clark County and the state capital of Helena on the north, Meagher County on the east, Jefferson County on the west, and Gallatin County and the city of Bozeman on the south.

The elevation in Broadwater County ranges from 3,800 feet above sea level in the valleys to 9,472 at the top of Mounty Baldy. The county is 1,238 square miles in size with 47 square miles being inland water retions. Four towns and communities are located within the county; Radersburg, Toston, Townsend and Winston