Big Sky is an unincorporated census-designated place (CDP) in Gallatin and Madison counties in southwestern Montana, United States. As of the 2010 census it had a population of 2,308. It is 45 miles (72 km) southwest of Bozeman. This unincorporated community straddles both counties, is not considered a town, and does not have a town government. The primary industry of the area is tourism.

Gallatin County is located in the U.S. state of Montana. With its county seat in Bozeman, it is the second-most populous county in Montana, with a population of 118,960 in the 2020 Census.