If Kadri wasn't exactly a hometown star when the Toronto Maple Leafs selected him with the No. 7 pick in the 2009 NHL Draft, he was close.

The feisty center is a native of London, Ontario, a two-hour drive from Toronto. In any case, those concerned liked what they saw from Kadri, who had 78 points (25 goals) for London of the Ontario Hockey League in his draft year. Returned to juniors for the 2009-10 season, Kadri finished his OHL career with a flourish, scoring 93 points (35 goals). He also helped Canada win a silver medal at the 2010 World Junior Championship.

Kadri made his NHL debut Feb. 8, 2010, against the San Jose Sharks, joining the Maple Leafs for one game before returning to juniors. Over the next three seasons, Kadri played for Toronto's American Hockey League affiliate in the city and the Maple Leafs.

Kadri got his first NHL point Nov. 16, 2010, on an assist against the Nashville Predators. Two days later he had two assists against the New Jersey Devils for his first multipoint NHL game. He scored his first NHL goal March 19, 2011, against Tim Thomas and the eventual Stanley Cup champion Boston Bruins.

Kadri had 44 points in 48 games during the lockout-shortened 2012-13 season, when he had two hat tricks. The first, which came during a seven-game point streak, came Feb. 28, 2013, against the New York Islanders. He had a natural hat trick and an assist March 30 against the Ottawa Senators.

Kadri reached 20 goals and 50 points for the first time in the NHL in 2013-14. He surpassed 50 points twice over the next five seasons (61 in 2016-17, 55 in 2017-18) and led the Maple Leafs with 45 points in 2015-16. Kadri played 10 seasons for Toronto before being traded to the Colorado Avalanche on July 1, 2019.

The following season, Kadri had NHL career highs of 59 assists and 87 points in 71 games. He had 15 points (seven goals, eight assists) in the 2022 Stanley Cup Playoffs, including a hat trick in Game 4 of the Western Conference Second Round, three points in a span of 2:04 in Game 2 of the Western Conference Final and the overtime winner in Game 4 of the Stanley Cup Final, less than three weeks after hand surgery. En route to helping the Avalanche win the Stanley Cup, Kadri advanced past the second round of the playoffs for the first time.

Kadri signed a seven-year, $49 million contract with the Calgary Flames on Aug. 18, 2022. He scored while  playing his 1,000th NHL game to help the Flames defeat the Columbus Blue Jackets 5-1 at Scotiabank Saddledome on Nov. 5, 2025. Kadri became the second Flames player to score while skating in the milestone game following Martin Gelinas, who accomplished the feat Dec. 9, 2003, and he was the 13th player in a Flames uniform to do so.

Kadri returned to the Avalanche when he was traded by the Flames on March 6, 2026. At the time of the deal, he was first on Calgary in points (41), assists (29), power-play points (13) and shots on goal (175).