[5] He made the team's active roster following training camp and played in his first career professional game on August 7, 2021, against the Calgary Stampeders.

[3] He later made his first career start on September 24, 2021, against the Montreal Alouettes at left guard.

[3] Giffen began the 2022 season on the injured list before being moved to the practice roster.

[7] He played and started in the last regular season game before moving back to the practice roster for the playoffs, where the Argonauts defeated the Winnipeg Blue Bombers in the 109th Grey Cup.

[9] He also played and started in all three post-season games that year, including the 111th Grey Cup where the Argonauts' defeated the Winnipeg Blue Bombers 41–24.