Stone Mountain is a city in DeKalb County, Georgia, United States. The population was 6,703 according in 2020. Stone Mountain is in the ea…Stone Mountain is a city in DeKalb County, Georgia, United States. The population was 6,703 according in 2020. Stone Mountain is in the eastern part of DeKalb County and is a suburb of Atlanta that encompasses nearly 1.7 square miles. It lies near and touches the western base of the geological formation of the same name. Locals often call the city "Stone Mountain Village" to distinguish it from the larger unincorporated area traditionally considered Stone Mountain and Stone Mountain Park.