Gloucester County is a county in the U.S. state of New Jersey. As of the 2020 census, the county was the state's 14th-most populous county with a population of 302,294, its highest decennial count ever and an increase of 14,006 from the 288,288 counted in the 2010 census, which in turn represented an increase of 33,615 from the 2000 census population of 254,673. Its county seat is Woodbury. The county is part of the South Jersey region of the state.