Junior After a highly successful 2018–19
minor hockey season with the Lévis Chevaliers of the
Quebec Junior AAA Hockey League (QMAAA), in which he set a franchise record for scoring as well as led the league in total points (88), Roy was selected first overall in the
Quebec Major Junior Hockey League (QMJHL) entry draft by the
Saint John Sea Dogs. Self-described as "not a physical guy really, more a skilled guy. Won't be making a lot of checks," Roy was compared to Sea Dogs alumni
Jonathan Huberdeau by team management. Conversely,
The Hockey News faulted the former's performance, writing that "despite posting 11 points in 11 playoff games, Roy left a lot to be desired and wasn't as competitive shift-to-shift as you'd like to see." Making his QMJHL debut in the
2019–20 season, he appeared in 60 games before the onset of the
COVID-19 pandemic curtailed the remainder of league play. At this juncture, Roy had 16 goals and 28 assists. At the beginning of the
2020–21 season, the
NHL Central Scouting Bureau rated Roy as a B-grade prospect, making him a candidate for selection in either the second or third round of the annual
NHL entry draft. He played 15 games with the Sea Dogs, registering nine goals and eight assists, before a shutdown of the team because of
COVID-19 pandemic outbreaks in New Brunswick that would last for almost four months. Roy struggled with the effects of the lockdown, ultimately requesting a trade, and, in advance of the 2021 trade deadline, was dealt to the
Sherbrooke Phoenix. He appeared in 16 games with the Phoenix, posting nine goals and 5 assists, second on the team in that timeframe. During the 2021 offseason, the Phoenix and Canadiens development staff collaboratively developed a program to address concerns about Roy's underlying training and conditioning. The league also awarded him the
Paul Dumont Trophy as the personality of the year, citing his status as "an important ambassador for the QMJHL" and "his positive impact in media circles." He was likewise a finalist for both the
Frank J. Selke Memorial Trophy, awarded to the most sportsmanlike player, and the
Michel Brière Memorial Trophy, awarded to the QMJHL's
most valuable player. In the ensuing
2022 QMJHL playoffs, the Phoenix reached the semi-finals, before being ousted by the
Charlottetown Islanders. During his penultimate
major junior campaign, Roy signed a three-year entry-level contract with the Canadiens on March 30, 2022. Following the QMJHL playoffs, he was eligible to be called up to play for the Canadiens'
American Hockey League (AHL) affiliate
Laval Rocket in the
Calder Cup playoffs. He appeared in one game in the Eastern Conference Finals. Returning to the Phoenix for the
2022–23 season, Roy soon received advice from Canadiens player development director Adam Nicholas that emphasized how to "build NHL habits to be a good NHL player." This included greater emphasis on physical play and entering "high danger" areas for generating offense. He appeared in only 55 regular-season games for the Phoenix that season, as a result of participating in the
2023 IIHF World Junior Championship, registering 46 goals and 53 assists and tied for seventh in league scoring. He received his second Dumont Trophy and second First All-Star Team designation, and was a finalist for the Brière Trophy for a second time. Roy and the Phoenix reached the playoff semi-finals for the second consecutive season, but were defeated by the
Halifax Mooseheads.
Professional After what was generally judged a successful time in the Canadiens' prospect camp, including leading the team in scoring at a rookie showcase tournament in
Buffalo, Roy was assigned to the AHL ranks for Laval's respective training camp in October 2023. During his
regular season debut with the Rocket, Roy registered a goal and an assist in a 7–3 loss to the
Abbotsford Canucks. He repeated this performance in the team's second game against the Canucks, attracting immediate positive commentary. On October 20, he scored his first AHL
hat-trick against the
Rochester Americans, also managing two assists in the game. For his efforts, Roy was subsequently named as the league's Rookie of the Month, having recorded five goals and seven assists through his first seven professional games. He went on to record 12 goals and 18 assists through 34 AHL games played, before being called up to make his NHL debut with the Canadiens on January 13, 2024, following an injury to
Josh Anderson. Roy scored his first NHL goal thereafter on January 17, a 3–2 victory over the
New Jersey Devils. After six games, he returned to the AHL, having had a goal and an assist in that span. He was recalled again on February 10 following an injury to
Rafaël Harvey-Pinard. Despite suffering an upper body injury in March, Roy returned in mid-April, and was one of four players reassigned to Laval to end the season. On October 7, Roy was again reassigned to the Rocket to begin the
2024–25 season following what had been considered an underwhelming preseason performance with the Canadiens. After posting 16 points through 17 games played with Laval, Roy was recalled by Montreal on November 25. Following a four-game stint with the Canadiens, he was reassigned to Laval on December 2. In early 2025, Roy was named to the
AHL All-Star Classic for the first time in his career. However, in a game versus the
Utica Comets just days later, he would suffer an upper-body injury, sidelining him for four to six weeks as a result. ==International play==