Brielle is a borough located in southern Monmouth County, New Jersey along the Manasquan River. As of the 2010 United States Census, the borough's population was 4,774, reflecting a decline of 119 from the 4,893 counted in the 2000 Census, which had in turn increased by 487 from the 4,406 counted in the 1990 Census.Brielle was formed as a borough by an act of the New Jersey Legislature on April 10, 1919, from portions of Wall Township, based on the results of a referendum passed on June 3, 1919. The borough was named for Brielle, a town in the Netherlands.