On February 28, 2017, at his introductory press conference, newly appointed head coach Marc Trestman declared Ray the Argos starting quarterback for the 2017 season: Despite Ray having only started 12 games over the previous two seasons. In the opening game of the season, Ray threw for a career-high 506 yards in a 32-15 win over the rival Tiger-Cats. On July 29, 2017, Ray surpassed Condredge Holloway to become the franchise leader in passing yards. Holloway threw for 16,616 yards between 1981 and 1986. On August 19, 2017, Ray became the Argonauts' all-time passing touchdown leader with his 99th touchdown pass, surpassing Holloway's 98. In that same game, he threw for his 100th touchdown pass as an Argonaut, becoming the first player in CFL history to throw at least 100 touchdown passes for two franchises. On October 21, 2017, Ray reached the 60,000 career passing-yard mark, becoming just the fourth player in CFL history to accomplish the milestone. In that same game, he also hit 5,000 passing yards for the season, joining Doug Flutie and Anthony Calvillo as the only players to pass for 5,000 yards at least four times in their careers. That game also marked the 12th time he eclipsed the 300-yard mark that season, which is an Argonauts record. The Argonauts finished the season 1st in the East with a 9-9 record, the only .500 team in the division. For his performance, Ray finished as runner-up to Edmonton quarterback Mike Reilly for the CFL's Most Outstanding Player Award. He would go on and win his fourth Grey Cup against the Calgary Stampeders in the 105th Grey Cup game. One day after the Argos Grey Cup parade, Ray conveyed to reporters that he was "seriously considering retirement". Ray, 38 years of age, who was a pending free agent for the 2018 season, said there was no timetable for a decision. On February 2, 2018 Ray and the Argos agreed to a one-year contract extension.