Brigantine is a city in Atlantic County in the U.S. state of New Jersey. As of the 2020 United States census, the city's population was 7,716, a de…Brigantine is a city in Atlantic County in the U.S. state of New Jersey. As of the 2020 United States census, the city's population was 7,716, a decrease of 1,734 from the 2010 census count of 9,450, which in turn reflected a decline of 3,144 from the 12,594 counted in the 2000 census. The city, and all of Atlantic County, is part of the Atlantic City-Hammonton metropolitan statistical area, which in turn is included in the Philadelphia-Reading-Camden combined statistical area and the Delaware Valley.