Mack attended Bishop Gorman High School in Summerlin, Nevada, where he went by Alizé Jones. He finished his high school career with 85 receptions for 1,725 yards and 27 TDs. In his senior year he was named to the U.S. Army All-American Bowl, USA Today All-USA First-team and First-team All-State after ending the season with 41 receptions, 930 yards and 13 TDs. At Bishop Gorman, Mack was teammates with fellow future Notre Dame football player Nicco Fertitta.
