McDavid's annual average value of $12.5 million will be the highest salary cap charge in the NHL.
"It's very well-deserved," Matthews told Sportsnet of McDavid's contract Sept. 8.
Matthews this season had 63 points (34 goals, 29 assists) in 62 games, having missed time with a back injury, a concussion and a right shoulder injury. He helped Toronto reach the Stanley Cup Playoffs for a second consecutive season, where it lost to the Boston Bruins in the Eastern Conference First Round.
Matthews, the No. 1 pick in the 2016 NHL Draft, can sign a multiyear extension and then before it begins would play the final season of his three-year, entry-level contract.
Toronto coach Mike Babcock met with Matthews at his home in Arizona last month to clear the air after reports surfaced of a rift between the two.
"Over [Auston's] career, over the time when I'm coaching him, there are going to be lots of times he's not happy," Babcock said May 14. "That's life. … When he wants to be pushed, he wants to be the best player he can be. That's what I'm going to do for sure. We're always going to continue to have dialogue. … We're all in it together."
McDavid, the No. 1 pick in the 2015 NHL Draft, this season led the NHL with 108 points (41 goals, 67 assists).