Harmon played for New Brighton before High School.
Harmon attended St Bede's College in Christchurch and during that time, he was selected as a member of the New Zealand Schools Barbarians squad for their matches against Australia and Samoa in 2012.[2]
After leaving school, Harmon played for New Brighton again in club rugby while working full-time as a plumber. He was in excellent form during the 2016 club rugby season, captaining New Brighton to the final of the Hawkins Division 1 Trophy. Unfortunately, the season didn't end well for him as he was red carded as his side went down to Lincoln University.[3]
His impressive club form didn't go unnoticed and through 2015 and 2016 he spent time with the Crusaders Academy and turned out for Canterbury's Colts and Maori sides.[1]
Senior career
Harmon was named in Canterbury's squad for the 2016 Mitre 10 Cup. He debuted in the first match of the season, a 43-3 victory over Auckland and went on to make 7 appearances and score 3 tries during the campaign which culminated in Canterbury lifting the Premiership title for the 8th time in 9 seasons as well as claiming the Ranfurly Shield.[4]
At the end of 2020, Harmon signed a two-year deal to play for the Highlanders in Super Rugby.