The 2005–06 Illinois State Redbirds men's basketball team represented Illinois State University during the 2005–06 NCAA Division I men's basketball season. The Redbirds, led by third year head coach Porter Moser, played their home games at Redbird Arena and competed as a member of the Missouri Valley Conference. They finished the season 9–19, 4–14 in conference play to finish in a tie for ninth place. They were the number ten seed for the Missouri Valley Conference tournament. They were defeated by the University of Evansville in their opening round game.