West Windsor is a township in Mercer County, New Jersey, United States. Located within the Raritan Valley region, the township is an outer-ring suburb of New York City in the New York metropolitan area, as defined by the United States Census Bureau. As of the 2010 United States Census, the township's population was 27,165, reflecting an increase of 5,258 (+24.0%) from the 21,907 counted in the 2000 Census, which had in turn increased by 5,886 (+36.7%) from the 16,021 counted in the 1990 Census.