Wisconsin's 4th congressional district is a congressional district of the United States House of Representatives in Wisconsin, encompassing a part of Milwaukee County and including almost all of the city of Milwaukee (except the slivers of the city in Waukesha and Washington counties), as well as its working-class suburbs of Cudahy, St. Francis, South Milwaukee, and West Milwaukee.

Recent redistricting has added the Milwaukee County North Shore communities of Glendale, Shorewood, Whitefish Bay, Fox Point, Bayside, and Brown Deer to the district.

With a Cook Partisan Voting Index rating of D+25, it is the most Democratic district in Wisconsin.

Barack Obama also swept the district in 2008, by a three-to-one margin over John McCain, with 75.39% of the vote to McCain's 23.61%.

Before the 2000 census, the 4th covered much of south Milwaukee, and extended into eastern Waukesha County.