The 2015 Illinois State Redbirds football team represented Illinois State University as a member of the Missouri Valley Football Conference (MVFC) during the 2015 NCAA Division I FCS football season.

Led by seventh-year head coach Brock Spack, the Redbirds compiled an overall record of 10–3 with a mark of 7–1 in conference play, sharing the MVFC title with North Dakota State for the second consecutive season.

Illinois State received an at-large bid to the NCAA Division I Football Championship playoffs.

After a first-round bye, the Redbirds defeated Western Illinois in the second round, before losing to Richmond in the quarterfinals.

The team played home games at Hancock Stadium in Normal, Illinois.