Mitchell attended Canterbury School in New Milford, Connecticut for his sophomore year of high school[5] before transferring to Brewster Academy in Wolfeboro, New Hampshire for his junior and senior years.[6] Along with basketball, he also played baseball in high school for two years, but focused on basketball when he went to Brewster, a move which garnered him more attention from college basketball coaches.[7][8] He committed to the University of Louisville to play college basketball.[9]