On September 11, 2015, Mitchell became the Timberwolves' interim head coach after Flip Saunders had to take a leave of absence to receive treatment after being diagnosed with Hodgkin's Lymphoma. On October 25, 2015, Saunders died at age 60. For the rest of the season, Mitchell became the official head coach, although he would still be treated as an interim coach. During his sole season coaching the Timberwolves, he would coach them to the fifth-worst record in the league with a 29–53 record.