Avenel is a census-designated place and unincorporated area within Woodbridge Township, in Middlesex County, New Jersey, United States. As of the United States 2000 Census, the CDP population was 17,552. East Jersey State Prison is located in Avenel, in the region bordering the city of Rahway.
Avenel is located at 40°34′58″N 74°16′47″W / 40.582660°N 74.279792°W / 40.582660; -74.279792 (40.582660, -74.279792).
According to the United States Census Bureau, the CDP has a total area of 9.0 km2 (3.5 mi2). 8.9 km2 (3.4 mi2) of it is land and 0.1 km2 (0.04 mi2) of it (0.58%) is water.