Tewksbury Township is a township located in Hunterdon County, in the U.S. state of New Jersey and is located within the New York Metropolitan Area. As of the 2020 United States census, the township's population was 5,870, a decrease of 123 (−2.1%) from the 2010 census count of 5,993, which in turn reflected an increase of 452 (+8.2%) from the 5,541 counted in the 2000 census.