Allendale is a census-designated place (CDP) in Ottawa County in the U.S. state of Michigan. The population was 27,073 at the 2020 census. It is located within Allendale Charter Township, occupying approximately 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. 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.