Chagnon played U Sports football with the Montreal Carabins where he was a member of the 50th Vanier Cup championship team.

Chagnon was selected in the third round and 24th overall by the BC Lions in the 2017 CFL Draft and signed with the team on May 23, 2017.

[2] Chagnon joined the Montreal Alouettes as a free agent on February 12, 2020.

[5] He scored his first career touchdown following a blocked punt on October 6, 2021 against the Toronto Argonauts.

[8] He began the 2022 season on the practice roster, but made his Alouettes debut in Week 3 after fellow linebacker Chris Ackie was moved to the injured list.