Leonia is a borough in Bergen County, New Jersey, United States. As of the 2010 United States Census, the borough population was 8,937. It is located near the western approach to the George Washington Bridge.
Leonia was formed as the result of a referendum passed on December 5, 1894, from portions of Ridgefield Township. Portions of Leonia were taken on February 19, 1895, to form the Township of Teaneck.
New Jersey Monthly magazine ranked Leonia as its 31st best place to live in its 2008 rankings of the "Best Places To Live" in New Jersey.