Big Foot Prairie is an unincorporated community and census-designated place in McHenry County, Illinois, United States. It was named a CDP for the 2020 census, at which time it had a population of 65. It is located in Chemung Township. Big Foot Prairie is located on U.S. Route 14, north of Harvard. The community extends north into Walworth County, Wisconsin, where there is a CDP of the same name in the town of Walworth.
The community is named for Big Foot, a Potawatomi leader who resided on nearby Kishwauketoe (today Geneva Lake in Wisconsin) until his band was forcibly removed by the United States in 1836. It once had a post office, which opened on May 15, 1848.
Big Foot Prairie first appeared as a census designated place in the 2020 United States census.