Belgrade is a city in Gallatin County, Montana, United States. The population was 10,460 at the 2020 census. Belgrade is part of the Bo…Belgrade is a city in Gallatin County, Montana, United States. The population was 10,460 at the 2020 census. Belgrade is part of the Bozeman, MT Micropolitan Statistical Area. It is the most populous city in Montana that is not a county seat.