Allendale is a census-designated place in Ottawa County in the U.S. state of Michigan. The population was 17,579 at the 2010 census. It is located within Allendale Charter Township, occupying the northern two-thirds of the township, from the eastern boundary with the Grand River west along Pierce St., north along 75th Ave., then west along Lake Michigan Drive to the western boundary of the township. It is a part of the Grand Rapids-Muskegon-Holland, Michigan combined statistical area, and is an exurb of Grand Rapids, due to its major commuter routes into the city.The ZIP code 49401 serves all of Allendale and many of the remnant portions of the township, as well as portions of Blendon Township to the south and Georgetown Township to the southeast.Allendale is named for the township.