Milwaukee County (/mɪlˈwɔːki/ ) is a county in the U.S. state of Wisconsin. The population was 939,489 at the 2020 census. It is both the most populous and most densely populated county in Wisconsin, containing about 15% of the state's population; it is also the 62nd-most populous county nationwide. The county seat is Milwaukee, the most populous city in Wisconsin. Named after the Milwaukee River, the county was created in 1834 as part of Michigan Territory and organized the following year. Milwaukee County is the most populous county of the Milwaukee metropolitan area, as well as of the Milwaukee–Racine–Waukesha combined statistical area.
Uniquely among Wisconsin counties, Milwaukee County is completely incorporated (i.e., no part of the county has the unincorporated "town" jurisdiction). There are 19 municipalities in Milwaukee County; 10 incorporated as cities and 9 incorporated as villages. After the city of Milwaukee, the most populous in 2020 were West Allis (60,325), Wauwatosa (48,387), Greenfield (37,803), Oak Creek (36,497), and Franklin (36,816). The county is home to two major-league professional sports teams, the Milwaukee Bucks and Milwaukee Brewers, and the world's largest music festival, Summerfest.