Milltown is a Borough in Middlesex County, New Jersey, United States. As of the 2010 United States Census, the borough population was 6,893.
Milltown was incorporated as a borough by an Act of the New Jersey Legislature on January 29, 1889, from portions of North Brunswick Township, based on the results of a referendum held three day earlier. The borough was reincorporated by resolution of the borough council on May 2, 1896. A portion of East Brunswick Township was annexed in 1902.
As of the 2000 Census, the center of population for New Jersey was located in Milltown, at Milltown Road, just east of the New Jersey Turnpike (see map of location).