The forward could have become a restricted free agent at the end of the season.
"I'm really glad we were able to make that happen," Kotkaniemi said Tuesday. "We have a great team here, we have a great young core. Eight years is a long time and I think we're going to have a great future on this team.
"It gives me a little peace, to work in peace, and focus fully on winning the Stanley Cup, chase a dream. That's great for me."
Hurricanes general manager Don Waddell said that signing Kotkaniemi for eight years was "the most important thing."
"We think this player has got good upside," Waddell said. "We kept pushing for eight years. Obviously the agent wasn't sure about eight years for a long time. We finally got him over the hump here to get an AAV that we were happy with and get him under a long-term contract.
"We think he's going to add to our offense. You've got to remember, he's still 21. He's only going to continue to get better. Where he tops off is still yet to be determined."
Kotkaniemi has scored 23 points (11 goals, 12 assists) in 59 games this season, tying his NHL career high in goals set as a rookie with the Montreal Canadiens in 2018-19.
"I keep reminding everyone that he's a young kid and he's only going to get stronger," Carolina coach Rod Brind'Amour said. "I think that means he's only going to get better. He knows how to play and he has a high skill level. He just needs to get a little stronger and a little quicker, all those things that, when you have those tools, will only make them better."
Selected by the Canadiens in the first round (No. 3) of the 2018 NHL Draft, Kotkaniemi has scored 85 points (33 goals, 52 assists) in 230 regular-season games and 12 points (nine goals, three assists) in 29 Stanley Cup Playoff games.
Kotkaniemi signed a one-year, $6.1 million contract with the Hurricanes on Aug. 28, 2021 after the Canadiens did not match an offer sheet. Montreal received a first-round pick and a third-round pick in the 2022 NHL Draft as compensation from Carolina.
"You're always weighing the risk versus the reward," Waddell said. "We see a higher projectile (projection) for this player. And as the seasons go on and the [NHL salary] cap continue to go up, we think these kind of players are going to become even more expensive."
Carolina forward Derek Stepan said he's impressed with how Kotkaniemi has played this season.
"When he has the puck on his stick, he's got a big body and he's able to create space a lot," Stepan said. "Obviously the talent is there. He shoots the puck well, he sees the ice well. But he has the ability to create himself five feet of space. That's a special trait.
"Very rarely do I have to come back to the bench and say, 'Did you see this or that,' because he was seeing it," Stepan said. "His game is really good, and I enjoy playing with him too."
The Hurricanes (41-15-6) are first in the Metropolitan Division. They host the Tampa Bay Lightning on Tuesday (7 p.m. ET; SNE, SNO, SNP, TVAS, BSSO, BSSUN, ESPN+, NHL LIVE).
