Rouyer was selected by the Edmonton Eskimos as the fourth overall selection of the 2019 CFL European draft and was signed by the team on May 16, 2019.[4][5] He made the team's active roster following training camp and made his professional debut on June 14, 2019, against the Montreal Alouettes.[3] Rouyer played in 17 regular season games and was credited with three special teams tackles, as well as both playoff games where he recorded another special teams tackle.[3] In the final regular season game of the year, Rouyer and teammate Diego Viamontes became the first Global teammates to be active in the same game.[3]
Rouyer did not play in 2020 following the cancellation of the 2020 CFL season. He re-signed with Edmonton on a contract extension through 2021 on December 26, 2020.[6] He played in one regular season game in 2021 where he had one special teams tackle. He was released on February 28, 2022.[7]
On May 19, 2022, the Panthers Wrocław announced that Rouyer had joined their 2022 roster.[8] He had 89 tackles, 4.5 sacks, and three fumble recoveries, including one that he returned for a touchdown.[9]
Following the end of the Panthers' 2022 season, Rouyer signed with the BC Lions on September 14, 2022.[10] He played in the final seven regular season games in 2022 where he had one forced fumble.[11] He also played in both playoff games that year where he had one special teams tackle.[11]
In 2023, he played in 11 regular season games where he recorded one defensive tackle and six special teams tackles.[11] He played in 16 regular season games in 2024 and had seven defensive tackles and 14 special teams tackles.[11]
On June 6, 2025, Rouyer was placed on the Lions' 1-game injured list to start the 2025 season. He rejoined the active roster on July 13, 2025. On September 11, 2025, Rouyer was again placed on the Lions' 1-game injured list. He rejoined the active roster on September 8, 2025.[12] On September 25, 2025, he was placed on the Lions' 1-game injured list for the third time that season, where he spent the remainder of the 2025 CFL season.[13] As a result of injuries, Rouyer played in just eight games where he had two special teams tackles.
Following the 2025 season, Rouyer was granted a one-time exemption where the league changed his roster status from Global to National.[14] This was more in line with the updated rule where a Non-Canadian player could be ruled as a National player if they had played at least three years of U Sports football.[14] Rouyer was the only player that would have qualified for this update.[14]
On February 10, 2026, Rouyer re-signed with the Lions, on a one-year contract extension.[15]
