Kadri has also represented Canada internationally at the 2010 World Junior Championships, where the team received the silver medal after losing the final to the United States 6–5.

From the beginning of the 2012–13 season to March 21, 2016, Kadri led the NHL in the number of penalties drawn with 164, 46 more than the second-placed player, Dustin Brown of the Los Angeles Kings.

[6] His grandparents were born in Kfar Danis, a mixed Muslim-Christian village in Lebanon, and moved to Ontario when Kadri's father was four years old.

[8] The Kadri family also attended National Hockey League (NHL) games; despite living near Toronto, they supported the Montreal Canadiens.

[13] During that year's playoffs, Kadri helped the Rangers to an OHL Championship and a berth in the Memorial Cup final, where they lost to the Spokane Chiefs of the Western Hockey League (WHL).

[16] He was selected to play for Team OHL in the ADT Canada Russia Challenge, but was unable to participate due to the jaw injury.

[16] Also during the 2008–09 season, Kadri was chosen to play in the OHL All-Star Classic, where he suited-up for the Western Conference and scored one goal.

He was selected to play for Team OHL in the 2009 Subway Super Series (renamed from the ADT Canada Russia Challenge).

[25] Due to injuries to forwards Christian Hanson and Fredrik Sjöström, Kadri was called-up to the Maple Leafs under an emergency basis, making his NHL debut on February 8, 2010, against the San Jose Sharks.

He did not register any points and finished with a −1 plus-minus rating while playing on a line with fellow rookie Viktor Stålberg and veteran Lee Stempniak.

[28][29] In addition, Burke was traditionally a strong supporter of rookies gaining experience at the American Hockey League (AHL) level prior to NHL careers.

[30] Kadri was included in the Maple Leafs' last round of cuts, and was subsequently sent to the AHL's Toronto Marlies for the start of the season.

Prior to 2012–13 season, Kadri began training under former NHL player and Maple Leaf Gary Roberts over the summer to gain muscle and "play more explosively".

He would score the first Maple Leafs goal of the season with a powerplay mark assisted by Phil Kessel against goaltender Carey Price.

With the Maple Leafs losing 4–1 late in the game, Hedman delivered a cross-check to the back of Kadri, who then confronted the 6 ft 6 in (1.98 m) defenceman.

Kadri was suspended twice during the 2014–15 season, the first internally by the organization for showing up late to a team practice; he received a three-game suspension.

[37] One week later, Kadri was suspended by the NHL: he received four games for illegally checking Edmonton Oilers forward Matt Fraser in the head.

[39] On April 4, 2016, Kadri was again suspended by the NHL after he delivered a cross-check to the head of Detroit Red Wings centre Luke Glendening.

Kadri received a four-game suspension for the incident, effectively ending his season, and as a repeat offender under the NHL Collective Bargaining Agreement, he was also fined $200,000.

During the 2017–18 season, Kadri scored his fourth career NHL hat-trick in a 6–3 win over the Columbus Blue Jackets on February 14, 2018.

[47] He found success with his new team, serving as their second-line center, recording 19 goals and 17 assists in his first 51 games, before missing the rest of the 2019–20 season due to a lower-body injury.

The regular season was itself prematurely ended by three weeks due to the COVID-19 pandemic restrictions, with the 2020 playoffs held later in the summer in a bubble in Edmonton, Canada at Rogers Place.

Kadri had 11 goals and 21 assists in all 56 games played, while the Avalanche enjoyed an excellent season and won the Presidents' Trophy as the best team in the league, narrowly prevailing over rivals the Vegas Golden Knights.

[55] As a result of the incident, Kadri received numerous racist and Islamophobic threats on social media by Blues fans, to the point that the matter was referred to the city police.

[62][63][64] Kadri, for his part, said that he desired to return to Colorado, but added "I've shown what my worth is and I'm just looking forward to watching this all develop.

[67] Kadri was invited to Canada's selection camp for the 2010 World Junior Championships held in Saskatoon and Regina, Saskatchewan.

Kadri did not elaborate on the specifics of what caused his refusal, but did absolve Niederreiter of using an ethnic slur: "Obviously, in big games like that, guys tend to lose their composure a bit, but I didn't take offence to anything he said.

"[71] During the gold medal game against the United States, Kadri had two assists including one on Jordan Eberle's game-tying goal with 1:35 left in the third period.

[74] Kadri is the fourth player of Lebanese descent to play in the NHL, following John Hanna, Alain Nasreddine and Ed Hatoum.