Sergeantsville is a historic unincorporated community located within Delaware Township, in Hunterdon County, in the U.S. state of New Jersey.

Delaware Township is a township in Hunterdon County, in the U.S. state of New Jersey. Part of the township is on the Hunterdon Plateau, while the southern portions are in the Amwell Valley. As of the 2020 United States census, the township's population was 4,560, a decrease of three people (−0.1%) from the 2010 census count of 4,563, which in turn reflected an increase of 85 (+1.9%) from the 4,478 counted in the 2000 census.