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 ZIP Codes.

Henry County is located in the north central portion of the U.S. state of Georgia. According to the 2020 census, the population of Henry County was 240,712, up from 203,922 in 2010. The seat of government is McDonough. The county was named for Patrick Henry.