Bound Brook is a borough in Somerset County, New Jersey, United States. As of the United States 2000 Census, the borough population was 10,155. Bound Brook was originally incorporated as a town by an Act of the New Jersey Legislature on March 24, 1869, within portions of Bridgewater Township. On February 11, 1891, it was incorporated as a borough, based on the results of a referendum held on the previous day.