Avenel is an unincorporated community and census-designated place located within Woodbridge Township, in Middlesex County, New Jersey, United States. As of the 2010 United States Census, the CDP's population was 17,011.East Jersey State Prison is located in Avenel, near the border of Rahway; Though located in Woodbridge Township, the prison's mailing address had led to it being called "Rahway State Prison". Also located in Avenel is the Adult Diagnostic and Treatment Center, which provides treatment to convicted sex offenders.