The 2021–22 Illinois Fighting Illini men's basketball team represented the University of Illinois in the 2021–22 NCAA Division I men's basketball season. Led by fifth-year head coach Brad Underwood, the Illini played their home games at the State Farm Center in Champaign, Illinois as members of the Big Ten Conference. They finished the season 23–10, 15–5 in Big Ten play to finish in a two-way tie for the regular-season championship. As the No. 1 seed in the Big Ten tournament, they were defeated by No. 9 seed Indiana in the Quarterfinals. They received an at-large bid to the NCAA tournament as the No. 4 seed in the South Region, where they defeated Chattanooga in the First Round before losing to Houston in the Second Round.