Fort Smith is a census-designated place (CDP) in Big Horn County, Montana, United States.

The North District of Bighorn Canyon National Recreation Area is accessed at Fort Smith.

Montana Highway 313 ends at Fort Smith and leads northeast 42 miles (68 km) to Hardin and Interstate 90.

The racial makeup of the CDP was 64.75% White, 32.79% Native American, 2.46% from other races.

37.3% of all households were made up of individuals, and 3.9% had someone living alone who was 65 years of age or older.