Mukwonago is a village in Waukesha and Walworth counties in the U.S. state of Wisconsin. It is along the Mukwonago River and Lower Phantom Lake. The population was 8,262 at the 2020 census, of which 8,040 were in Waukesha County and 222 were in Walworth County. The village is located mostly within the Town of Mukwonago in Waukesha County, with a small portion extending into the Town of East Troy in Walworth County.