Billy Harmon joined the Highlanders for the 2021 Super Rugby Season, after three seasons with the Crusaders, and was awarded Defender of the Year after a stand-out season. A delayed start to the 2022 season through injury saw Billy return to the team in mid-April and quickly re-established himself as a vital member of the forward pack.

Billy has been a member of the Māori All Blacks since 2018 and was again selected in 2022 to play in the two test series against Ireland in June. 

The reliable openside flanker Captained the Canterbury team in the Bunnings NPC and led them to the 2022 final. 

Billy will take on a new role in 2023 as the Highlander's Captain.