Big Horn Peak is a 9,935-foot (3,028-metre) mountain summit in Gallatin County, Montana, United States.

Big Horn Peak is located 40 miles (64 km) south of Bozeman in the Gallatin Range, which is a subrange of the Rocky Mountains.

Precipitation runoff from the mountain's north slope drains to the Yellowstone River via Tom Miner Creek, whereas the other slopes drain into tributaries of the nearby Gallatin River.

Topographic relief is significant as the summit rises over 2,300 feet (701 meters) above North Fork Specimen Creek in 1.5 miles (2.4 km) and 1,300 feet (396 meters) above the headwaters of Tom Miner Creek in 0.5 miles (0.80 km).

[4] The mountain's toponym was officially adopted on May 7, 1930, by the United States Board on Geographic Names.