The 28th Senate District of Wisconsin is one of 33 districts in the Wisconsin Senate. Located in southeast Wisconsin, the district comprises southeast Waukesha County and northwest Racine County. It includes the cities of Muskego, New Berlin, and most of the city of Waukesha, along with the villages of Big Bend, Mukwonago, and Waterford.

The Wisconsin Senate is the upper house of the Wisconsin State Legislature. Together with the larger Wisconsin State Assembly they constitute the legislative branch of the state of Wisconsin. The powers of the Wisconsin Senate are modeled after those of the U.S. Senate.