Griffin is a city in and the county seat of Spalding County, Georgia, United States. It is part of the Atlanta metropolitan area. As of the 2020 cens…Griffin is a city in and the county seat of Spalding County, Georgia, United States. It is part of the Atlanta metropolitan area. As of the 2020 census, the city had a population of 23,478. Griffin was founded in 1840 and named for landowner Col. Lewis Lawrence Griffin.