Northlake is a suburban area located in central Anderson County, bordering the north side of Anderson, the county seat. Northlake is a census-designated place (CDP) located on both sides of an arm of Lake Hartwell, a large reservoir and recreation area. Interstate 85 forms the northern boundary of the CDP, leading northeast 27 miles (43 km) to Greenville and southwest 120 miles to Atlanta. Exits 19 (U.S. Route 76) and 21 (U.S. Route 178) serve the community.
According to the United States Census Bureau, the CDP has a total area of 5.2 square miles, of which 4.1 square miles is land and 1.0 square mile, or 20.42%, is water. Darwin Wright Park, a City of Anderson recreation area, provides access within the CDP to Lake Hartwell on its arm formed by Six and Twenty Creek.