Hunterdon County is a county located in the western section of the U.S. state of New Jersey. At the 2020 census, the county was the state's 18th-most populous county, with a population of 128,947, its highest decennial count ever and an increase of 598 from the 2010 census count of 128,349, which in turn reflected an increase of 6,360 from the 121,989 counted in the 2000 census. Its county seat is Flemington. The county is part of the Central Jersey region of the state.