McCormack fought for Great Britain in the light welterweight category at the 2016 Rio Olympics, defeating Ablaikhan Zhussupov from Kazakhstan in his opening bout before losing via split decision in the round-of-16 to Cuban boxer Yasniel Toledo.

[3] Representing England, McCormack won a gold medal in the welterweight division at the 2018 Commonwealth Games, with a win over Northern Ireland’s Aidan Walsh in the final.

[6][7][8] At that year's World Championships in Yekaterinburg, Russia, he won the silver medal after losing 4:0 to Russian boxer Andrey Zamkovoy in the welterweight final which was stopped in the second round due to a cut suffered by McCormack following an accidental clash of heads.

[17] Undefeated after five fights, he secured a unanimous decision win over Williams Andres Herrera in a 10 round contest at the Co-op Live Arena in Manchester on 26 October 2024.

[18] At the same venue on 15 February 2025, McCormack defeated Robbie Davies Jr, knocking his opponent to the canvas three times during the contest which was halted by corner retirement at the end of round six.