Delafield is a city in Waukesha County, Wisconsin, United States, along the Bark River. The population was 7,185 at the 2020 census. It is pa…Delafield is a city in Waukesha County, Wisconsin, United States, along the Bark River. The population was 7,185 at the 2020 census. It is part of the Milwaukee metropolitan area. The city of Delafield is a separate municipality from the Town of Delafield, both of which are situated in township 7 North Range 18 East.