The 24-year-old defenseman could have been a restricted free agent July 28. He scored six points (two goals, four assists) in 51 games this season and did not have a point in three Stanley Cup Playoff games.
"I think a shorter deal is better for me now," Dermott said. "I feel like I still have a lot to prove to myself and everyone, so I think taking a short deal is better. ... I've got confidence in my game and where it's going to take me. It's nice to get two years and kind of bear down and see what I can do with myself and the team. It's nice to have a nice chunk of time ahead of me.
"I felt like I had a pretty good season. The ups and downs happen, but looking back, I felt good, I kind of found my game a little bit more. ... I feel like my defensive game got better, my confidence going back into the [defensive] zone and trusting my feet instead of just tightening up and holding on to the puck, making sure I'm not making the wrong play. That's when you're going to end up making more wrong plays than you're trying to avoid."
Dermott was selected by the Maple Leafs in the second round (No. 34) of the 2015 NHL Draft. He's scored 47 points (11 goals, 36 assists) in 208 regular-season games and five points (two goals, three assists) in 22 playoff games.
He said he is not concerned about possibly being left unprotected in the 2021 NHL Expansion Draft on July 21 that will stock the initial roster of the Seattle Kraken, who begin play next season. NHL teams, with the exception of the Vegas Golden Knights, who are exempt, must submit their protected lists of seven forwards, three defenseman and one goalie, or eight skaters and one goalie, by July 17.
"You never know what's going to happen,during a game, the trades after, anything could happen," he said. "It's in the back of my mind that it is a possibility I could get picked and I certainly didn't get any assurances I wasn't going anywhere, that's for sure.
"If it happens, it happens. ... I'm happy to be here, happy to be back for another couple of years. It's where I want to be, where all my family is and where the best fans in hockey are, so it's exactly where I want to be and honored to be back for another couple of years."
NHL independent correspondent Dave McCarthy contributed to this report