Saint Mary Peak is a 9,351-foot elevation (2,850 m) mountain summit located in Ravalli County, Montana.

Saint Mary Peak is located in the Bitterroot Range, which is a subset of the Rocky Mountains. It is situated eight miles west of Stevensville in the Selway–Bitterroot Wilderness, on land managed by Bitterroot National Forest. The summit lies five miles east of the Idaho–Montana border. Precipitation runoff from the mountain drains into tributaries of the Bitterroot River. Topographic relief is significant as the summit rises over 5,000 feet (1,500 meters) above Big Creek in three miles. A popular 3.5-mile hiking trail leads to a fire lookout tower at the summit. The lookout was originally built in 1931 and reconstructed in 1953, and was placed on the National Register of Historic Places in 2018. This landform's toponym has been officially adopted by the United States Board on Geographic Names.

Based on the Köppen climate classification, Saint Mary Peak is located in a subarctic climate zone characterized by long, usually very cold winters, and mild summers. Winter temperatures can drop below −10 °F with wind chill factors below −30 °F.

• Geology of the Rocky Mountains
• National Register of Historic Places listings in Ravalli County, Montana

• Weather forecast: Saint Mary Peak
• Saint Mary Peak Trail: Hikingproject.com