On September 25, 2016, Fortin signed a three-year contract with the Blackhawks as an undrafted free agent.[3] He was assigned to their American Hockey League affiliate, the Rockford IceHogs, to start the 2017–18 season with.
In the following 2018–19 season, on October 9, 2018, after Andreas Martinsen suffered a back injury, he was recalled from the IceHogs by Chicago.[4] He recorded his first career NHL goal on October 21, in a 6-3 loss to the Tampa Bay Lightning.[5]
Following the conclusion of his entry-level contract with the Blackhawks, Fortin as an impending restricted free agent was not tendered a qualifying offer and was released to free agency. Approaching the delayed 2020–21 season, Fortin was signed to a one-year contract to continue in the AHL with the Colorado Eagles, the primary affiliate to the Colorado Avalanche on January 6, 2021.[6] In the pandemic delayed 2020–21 season, Fortin struggled to find his role within the Eagles, registering just 3 assists in 23 regular season games. He made one post-season divisional playoff game appearance before leaving the club at the conclusion of his contract.
As a free agent, Fortin continued within the AHL, securing a one-year contract with hometown provincial club, the Laval Rocket, on July 6, 2021.[7] On August 22, 2022, the Hershey Bears signed Fortin. [8]
On September 19, 2023, Fortin continued his career in the minor league by agreeing to a one-year contract with the Orlando Solar Bears of the ECHL.[9]