Harrington represented New Zealand at the 2020 Winter Youth Olympics and was the flag-bearer during the closing ceremony. During the Youth Olympics he won a bronze medal in the halfpipe event with a score of 80.66 points.[3]
During the 2024–25 FIS Freestyle Ski World Cup, he won the big air crystal globe with 390 points. He became the first New Zealander to win a crystal globe at the FIS Freestyle Ski World Cup.[4][5]
In January 2025, he competed at the Winter X Games, where he was a late substitution for an injured athlete. During the slopestyle competition he landed a triple cork 1620 and won a gold medal with a score of 93.33 points.[6][7] In March 2025, he competed at the 2025 FIS Freestyle Ski World Championships and won a gold medal in the big air event with a score of 192.00 points.[8] He again competed at the 2026 Winter X Games and won a gold medal in slopestyle, and a silver medal in the big air event.[9]
In January 2026, he was selected to represent New Zealand at the 2026 Winter Olympics.[10] He competed in the slopestyle event and won a bronze medal with a score of 85.15.[11] He then competed in the big air event. During qualification he ranked fifth with a score of 179.75 points and advanced to the finals.[12]