Dunellen is a Borough in Middlesex County, New Jersey, United States. As of the United States 2000 Census, the borough population was 6,823.
Dunellen was formed as a borough by an Act of the New Jersey Legislature on October 28, 1887, when it broke away from Piscataway Township, based on the results of a referendum held on March 23, 1886. Dunellen's incorporation was confirmed on April 15, 1914.
Dunellen is located at 40°35′23″N 74°27′59″W / 40.589702°N 74.466349°W / 40.589702; -74.466349 (40.589702, -74.466349).