In his first full season with the Canadiens, Reilly skated in 57 games and registered 11 points. He averaged nearly 19 minutes per game and posted an impressive Corsi For rating of 54.8, according to Natural Stat Trick.
The 25-year-old was traded from the Minnesota Wild to the Canadiens prior to the 2018 trade deadline in exchange for a fifth-round pick.
Reilly was one of Montreal's four restricted free agents along with forwards Charles Hudon, Artturi Lehkonen, and Joel Armia. With Reilly signed, the Canadiens now have eight defensemen under contract for next season. Veteran blue-liner Jordie Benn is the team's lone unrestricted free agent.