On July 15, 2017, during a Week 4 match against the Hamilton Tiger-Cats, Lulay set a new CFL record for most passing yards when coming off the bench. He threw 436 passing yards (a career-high) after replacing Jennings who left the game due to injury, helping the Lions win the game 41–26. Lulay started the next three games for the Lions, winning two of them, before a suffering a minor shoulder injury, which coincided with Jonathon Jennings' return to health in Week 8. Nevertheless, Jennings struggled in the next three games, resulting in Lulay being forced into action in all three matches (all of which were losses). With Lulay having greatly outplayed Jennings head coach Wally Buono announced Lulay as the starter for the team's Week 12 match against Montreal. However, Lulay suffered a non-contact injury to his knee early in the game and did not return. On September 12, 2017, the Lions announced that Lulay would miss the remainder of the season with a torn ACL, which required surgery and minor damage to his MCL, which did not require surgery.