Allendale is an unincorporated community in Ottawa County in the U.S. state of Michigan. It is also a census-designated place (CDP) for statistical purposes. The population was 17,579 at the 2010 census. The community is located within Allendale Charter Township and the CDP area consists of about 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 (M-45) to the western boundary of the township. Apart from the CDP definition, the community is centered at the intersection of M-45 and 68th Ave., which are the only roads which cross the Grand River in the county east of Grand Haven. 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 (M-45 and I-96).
The Allendale ZIP code 49401 serves all of the CDP. The 49401 ZIP code also serve portions of southern Allendale Township not included in the CDP as well as portions of Blendon Township to the south and Georgetown Township to the southeast.
Allendale is named for the township. Malta was initially chosen as the name for the township, however when the township was organized in 1849, state senator Pennoyer changed the name to Allendale, after Agnes Allen, the first person on the tax roll in the area and the widow of Hannibal Allen, who was the son of Revolutionary War hero Ethan Allen.