McDonough is a city in Henry County, Georgia, United States. It is part of the Atlanta metropolitan area. Its population was 22,084 at the 2010 census, up from 8,493 in 2000. The city is the county seat of Henry County. The unincorporated communities of Blacksville, Flippen, Kelleytown, and Ola are located near McDonough, and addresses in those communities have McDonough postal codes.
The town was named for naval officer Commodore Thomas Macdonough and founded in 1823 around a traditional town square design. The buildings surrounding the square are intact, although there are some vacancies. The county courthouse and historic jail building are on the north side near the Welcome Center in a historically maintained Standard Oil service station, built in 1920. The station also houses the Main Street Program Office and Hospitality and Tourism Office.