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.

There were 68.2% of families and 50.0% of the population living below the poverty line, including 55.1% of under eighteens and none of those over 64.