From Wikipedia, the free encyclopedia. Muskego is a city in Waukesha County, Wisconsin, United States. As of the 2010 census, the city had a population of 24,135. Muskego is the fifth largest community in Waukesha County. The name Muskego is derived from the Potawatomi Indian name for the area, Mus-kee-Guaac, meaning sunfish. The Potawatomi were the original inhabitants of Muskego.