Fulton County is a county in the north-central portion of the U.S. state of Georgia. As of the 2020 United States census, the population was 1,066,710, making it the state's most populous county and its only one with over one million inhabitants. Its county seat and largest city is Atlanta, the state capital. About 90% of the City of Atlanta is within Fulton County; the other 10% is in DeKalb County. Fulton County is part of the Atlanta–Sandy Springs–Roswell, GA Metropolitan Statistical Area.