[5] As part of the 2021 Canadian Olympic swimming trials in Toronto, Knox broke the national record in the 200 individual medley event, with a time of 1:58.07.

[6][7][8][9] Knox placed seventeenth in the heats of the men's 200 m individual medley, 0.14 seconds behind Japan's Daiya Seto, and thus missed qualifying to the semi-finals.

He said afterward that a series of disappointments at recent championships had "lit a fire in my stomach and coming into this worlds I just didn’t want to let that happen again.

[16] Subsequently, Knox was part of the Canadian delegation to the 2023 Pan American Games, where he won four bronze medals in relay events and took the gold in the 200 m individual medley.

[17] While many of Canada's top swimmers opted to skip the 2024 World Aquatics Championships in Doha, Knox was named to the team.