South Hackensack is a township in Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 2,701, an increase of 323 (+13.6%) from the 2010 census count of 2,378, which in turn reflected an increase of 129 (+5.7%) from the 2,249 counted in the 2000 census.