Mannington Township is a township in Salem County, New Jersey, United States. As of the 2010 United States Census, the township's population was 1,806, reflecting an increase of 247 (+15.8%) from the 1,559 counted in the 2000 Census, which had in turn declined by 134 (-7.9%) from the 1,693 counted in the 1990 Census.
Mannington Township was first mentioned on May 12, 1721. It had been previously known as East Fenwick Township, which was mentioned on September 3, 1679, though the details of its incorporation are unknown. The township was incorporated by an Act of the New Jersey Legislature on February 21, 1798 as one of New Jersey's original group of 104 townships. A portion of the township was taken in 1878 and annexed by Quinton Township. Mannington Township is a dry town where alcohol cannot be sold.