The 1984–85 Illinois State Redbirds men's basketball team represented Illinois State University during the 1984–85 NCAA Division I men's basketball season. The Redbirds, led by seventh year head coach Bob Donewald, played their home games at and were a member of the Missouri Valley Conference. The Redbirds received an at-large bid to the 1985 NCAA Division I men's basketball tournament. They were assigned to the Midwest Regional as the number nine seed where they defeated the University of Southern California in the first round and lost to the University of Oklahoma in the second round.