Pompton Plains is a census-designated place (CDP) comprising the majority of Pequannock Township, Morris County, New Jersey, United States. It is in the valley of the Pompton River, which forms the eastern border of the community, the township, and Morris County. Across the river to the east is Wayne in Passaic County, and across the river to the northeast is the borough of Pompton Lakes. Neighboring communities in Morris County are Riverdale to the north, Kinnelon to the west, Lincoln Park to the southwest, and the remainder of Pequannock Township to the south.