Belmont is a census-designated place (CDP) in Loudoun County, Virginia, United States. As of the 2020 census, Belmont had a population of 10,268. It is 5 miles (8 km) southeast of Leesburg, the Loudoun county seat, and 31 miles (50 km) northwest of Washington, D.C. The Belmont Manor House, built between 1799 and 1802 by a son of Richard Henry Lee, is in the northeast part of the CDP and is now the clubhouse for a gated golf community.