The 19-year-old forward, who was the No. 3 pick in the 2018 NHL Draft, has eight points (six goals, two assists) in 36 games this season. He had 34 points (11 goals, 23 assists) in 79 games as a rookie in 2018-19.
Kotkaniemi, who missed eight games with a concussion in December, has one goal in his past 12 games and was a healthy scratch against the Buffalo Sabres on Thursday.
"So that's the problem here, we always look at the negative versus a positive, and right now it's about a kid who has had a couple of injuries that hasn't quite found his game, is probably losing confidence too," Canadiens coach Claude Julien said about sending Kotkaniemi to the AHL for the first time in his professional career.
"So we want him to gain some confidence. We want him to find his game so there's nothing negative about that. I think it's more positive and that's what we need to see. He's got great potential and that hasn't changed from day one. I think he's had a rough start like some players have in different teams, different years, they start off with some major injuries or injuries that set them back, and they never seem to be able to get their rhythm going again.
"And I think as a young player you don't want him losing his confidence, you want him to find his game back, and I think the best way to do that is go down there, play a lot, and regain your confidence. And when you do, we'll be more than happy to throw you in the lineup and put you where you belong, in the NHL."
The Canadiens (24-22-7) defeated the Florida Panthers 4-0 on Saturday in the first game of a stretch when they play five of six at home. They are six points out of the second wild card into the Stanley Cup Playoffs from the Eastern Conference.
"In the next couple of weeks, it's about trying to put the best team on the ice for this specific game to counter the other team. And if we're going to make a [playoff] push, that's how we have to think," Julien said. "We can't think about who we're sitting out and what it does and what the perception is.
"I think right now it's let's give it a push and then in a week or two from now we'll know whether we're back in the [playoff] race or not. And then we can manage our lineup appropriately after that happens."
NHL.com independent correspondent Sean Farrell contributed to this report