McCann has signed an extended deal that ties him to McDiarmid Park until the summer of 2023.
The 20-year-old has made 18 first-team appearances and made his Northern Ireland Under-21 debut this season after returning from a loan spell at Stranraer.
Wright told St Johnstone's website: "It's a great bit of business and he deserves his new contract. In my opinion he's been the best and most consistent young player in the league since he broke into the team.
"He's shown great maturity in his performances despite the team not doing as well as we'd like. He is growing and growing, and getting better with each game.
"I spoke to Ali at the end of last season and told him it was going to be a big year for him. I told him he'd get opportunities and it was up to him to take them which he has.
"In my mind I was thinking that maybe 15 to 20 appearances this season would be a good step up for him from playing with Stranraer in League One but he's been almost ever-present since he first came into the side.
"And that's down to him because he's worked extremely hard. He's really easy to work with and he has a great attitude. I'm really pleased for him and for me I'm just delighted to have one of the club's most exciting young players tied up."