Mackey has played in 39 career NHL games over three seasons split with the Flames and Coyotes, notching 11 points (4G-7A). The Tower Lake, Illinois native has played two seasons at the AHL level with the Stockton Heat, compiling 52 points (8G-44A) in 80 games. In 2021-22 with Stockton, he led team defensemen with 36 points (5G-31A) in 53 games. He was named an AHL All-Star in 2021.