The 18-year-old forward practiced on a line with forwards Christian Dvorak and Brendan Gallagher and was not among the final cuts Monday. The Canadiens begin the season at home against the Toronto Maple Leafs on Wednesday (7 p.m. ET; SN, TVAS, ESPN+, SN NOW).
"It feels really, really great," Slafkovsky said. "I would say that I always believed and I'm happy that I know how it is and there is some work to do starting Wednesday."
Slafkovsky, who is from Slovakia, texted his parents "that they can come now."
"I'm sure they will do their best and I hope they will be here," he said.
Slafkovsky had two assists and 12 shots on goal in six preseason games. He scored seven goals in seven games for Slovakia at the 2022 Beijing Olympics, winning MVP honors and helping his country win a bronze medal. He had seven points (two goals, five assists) in 18 playoff games last season in Liiga, Finland's top professional league.
"I'll just play my best game every time I get the chance to play," Slafkovksy said. "I think if I give everything then I can stay here for a long time, and that's what I will try to do."
He is one of four rookies who made the opening night roster. Defensemen Kaiden Guhle, Jordan Harris and Arber Xhekaj are the others.
Coach Martin St. Louis gave all four players the news at the same time.
"It was pretty special to get to hear it with those guys too," Guhle said. "Your dream as a kid is to play in the NHL, so obviously it's cool and definitely a dream come true to hear that news this morning and I was very excited for sure."
St. Louis said he wanted the rookies to share their special moment.
"I think if you bring them in one at a time they'll think they've been cut," St. Louis said. "It's always more fun to celebrate as a group. When you have a big moment like that it's always fun when there are people around you. A moment like that by yourself isn't as much fun."
Defensemen Justin Barron and Otto Leskinen, forwards Rafael Harvey-Pinard and Jesse Ylonen, and goalie Cayden Primeau were assigned to Laval of the American Hockey League.
Forward Nick Suzuki practiced after missing two preseason games with a lower-body injury. Dvorak and forward Mike Hoffman also returned to practice.
Defenseman Mike Matheson is day to day with a lower-body injury.
Forward Joel Armia was placed on injured reserve because of an upper-body injury. Forward Emil Heineman is out six weeks with a thumb injury.
Defenseman Joel Edmundson (lower body) skated but there is no timeline for his return.
