The 27th Senate District of Wisconsin is one of 33 districts in the Wisconsin Senate. Located in south-central Wisconsin, the district comprises most of the northwest quadrant of Dane County. It includes much of the west side of the city of Madison, as well as portions of Madison's far north side. The 27th also includes the suburban cities of Middleton and Verona, and the villages of Black Earth, Cross Plains, Dane, Mazomanie, and Waunakee.

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.