Branchburg is a township in Somerset County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 14,940, its highest decennial census count ever and an increase of 481 (+3.3%) from the 2010 census count of 14,459, which in turn had reflected a decline of 107 (−0.7%) from the 14,566 counted at the 2000 census.