Schenn, projected as the NHL's best rookie in some publications, missed the last two preseason games with a left shoulder injury.
"He needs to play a little bit," general manager Paul Holmgren said. "I don't know how long that's going to be, but he's healthy now, and he's ready to take part in things."
If he plays one game in the AHL, Schenn's cap-hit for the year drops from $3.1 million to $1.69 million because of the bonus structure set up by the Kings contract.
Schenn's demotion opens a spot for Couturier, the 18-year-old center selected with the No. 1 draft pick acquired from Columbus in the Jeff Carter trade.
"It was a good camp overall for me, but I have to do even better now to stay up here," Couturier said.
Coach Peter Laviolette said Couturier "responded well in all situations," including the power play and penalty kill.
Once Couturier plays in his 10th game (not the team's), a year of his contract will be on the books. When he plays in his 11th game, he counts toward the 50-man reserve list.
At Tuesday's practice, Danny Briere was centering Jakub Voracek and Wayne Simmonds, and Claude Giroux was centering James van Riemsdyk and Jaromir Jagr.
The third line had Matt Read with Scott Hartnell and Andreas Nodl. Couturier is expected to center the third line in Thursday's opener in Boston. The fourth line could have Max Talbot centering Nodl and Zac Rinaldo.
Contact staff writer Sam Carchidi at firstname.lastname@example.org or @BroadStBull on Twitter.