Matawan is a borough in Monmouth County, in the U.S. state of New Jersey. A historic community located near the Raritan Bay in the much larger Raritan Valley region, the borough is a commuter town of New York City within the New York Metropolitan Area. As of the 2020 United States census, the borough's population was 9,565, an increase of 755 from the 2010 census count of 8,810, which in turn reflected a decline of 100 from the 8,910 counted in the 2000 census.