Armia playing for Porin Ässät in 2010, as a 17-year-old.
In the 2008–09 season, Armia was the highest goal scoring player of the U16 SM-sarja with 27 goals, winning the Keijo Kuusela award. In the following season, Armia played 27 games with Ässät U20, recording 15 goals and six assists for a total of 21 points.
At the age of 17, Armia was promoted to Porin Ässät's roster in SM-liiga in the 2010–11 season after showing great talent in the Ässät junior teams and the Finnish national team.[2] Armia would record 18 goals and 11 assists in his rookie season, being the highest goal-scoring rookie in the league. He played five playoff games scoring two goals. Armia was selected 16th overall by the Buffalo Sabres of the National Hockey League (NHL) in the first round in the 2011 NHL Entry Draft and 14th overall by the Severstal Cherepovets of the Kontinental Hockey League (KHL) in the 2011 KHL Junior Draft.[3][4] In the following season Armia played in 54 regular season games and recorded 18 goals and 20 assists for 38 points with Ässät. Armia appeared in three playoff games putting up two assists. In June 2012, Armia signed with the Buffalo Sabres,[5] but would play with Ässät on a loan for one more season. Armia played in 47 regular season games recording 19 goals and 14 assists for a total of 33 points. He was instrumental in helping Ässät capture SM-liiga's Kanada-malja championship after finishing fourth in the regular season. In the playoffs, Armia recorded three goals with five assists in 16 playoff games.[6][7] During his time with Ässät, he had career totals of 55 goals, 45 assists, for 100 points, with 120 penalty minutes.
While in Ässät, Armia was considered one of the most talented players of his age group in the world and a future superstar by media.[2][8] Armia has been considered a natural goal scorer.[9] Eric Weissman, a former scout for the Buffalo Sabres, highlighted Armia's puck possession abilities. In the same article by The Athletic, Armia was called a pure skill player.[10]
On 16 June 2012, Armia was signed to a three-year entry-level contract with the Sabres.[5] He would record seven goals and 20 assists for the Sabres' American Hockey League (AHL) affiliate, the Rochester Americans, during the 2013–14 AHL season. He also participated in the 2013 Spengler Cup with Rochester, scoring one goal.[11] During his second North American professional season in 2014–15, Armia was recalled from the Rochester Americans, and made his NHL debut with the Sabres against the Detroit Red Wings on 23 December 2014.[12] He was then returned to the Americans before being traded to the Winnipeg Jets on 11 February 2015.[13][14]
After being acquired in the blockbuster deal involving Evander Kane and Zach Bogosian, Armia was assigned to Winnipeg's AHL affiliate, the St. John's IceCaps, and finished the season with them. Armia began the 2015–16 season with Winnipeg's new AHL affiliate, the Manitoba Moose where he was used as a penalty killer.[15] He was recalled by the Jets that season and scored his first NHL goal against Martin Jones in a 4–1 win over the San Jose Sharks on 3 January 2016.[16] The 2016–17 season was Armia's first full year in the NHL. He struggled early, getting scratched in the second game of the season, and missed 24 due to injury. However, his scoring picked up in the second half of the season while playing on a line with Adam Lowry and Shawn Matthias (who was replaced by Andrew Copp after Matthias suffered an injury).[15] Armia improved again during the 2017–18 season, finishing with 12 goals and 29 points in 79 games.[17]
On 30 June 2018, the Jets traded Armia to the Montreal Canadiens.[18][19] On 13 July 2018, Armia signed a one-year contract worth $1.85 million with the Canadiens.[20][21] On 6 October, Armia scored his first goal for Montreal, a shorthanded goal that gave the Canadiens a 4–0 lead over the Pittsburgh Penguins en route to a 5–1 victory.[22] On 1 November, Armia and teammate Max Domi scored the fastest two goals by one team when Montreal defeated the Washington Capitals, 6–4.[23] Domi scored at 19:38 of the third period, and Armia clinched the win with an empty net goal two seconds later.[24] Armia converted the decisive goal in the fifth round of a shootout victory against the New York Islanders on 5 November; he was the only player from either team to beat the goaltender.[25] However, in the Canadiens' next game, against the New York Rangers on 6 November, Armia suffered a knee injury. He was initially expected to miss six to eight weeks, and ultimately missed 25 games.[26] In December 2018, HC CSKA Moscow bought Armia's KHL rights from Severstal Cherepovets, even though Armia never left for the KHL.[27][28] On 3 January 2019, Armia returned from injury against the Vancouver Canucks; he was credited with an assist on Jordie Benn's opening goal in a 2–0 Montreal win.[29] On 1 March, Armia scored his first career NHL hat trick in a 4–2 victory against the New York Rangers.[30]
On 11 July 2019, Armia signed a two-year contract worth $5.2 million with the Canadiens. He had previously filed for salary arbitration as a restricted free agent.[31][32] Armia scored his first two goals of the 2019–20 season in a 5–4 overtime loss to the Buffalo Sabres on 9 October.[33]
After recording seven goals and seven assists during the 2020–21 season, Armia managed five goals and three assists during the Canadiens' deep run to the 2021 Stanley Cup Finals during the 2021 Stanley Cup playoffs. On 27 July 2021, Armia signed a four-year, $13.6 million contract extension with the Canadiens.[34]
Before the start of the 2023–24 season, the Canadiens placed Armia on waivers for the purpose of re-assignment to the AHL affiliate, the Laval Rocket. Armia cleared waivers.[35][36][37] In his first AHL game with the Rocket, Armia scored two goals.[38] He played four games with Laval registering four goals and five total points before being called up to the Canadiens squad again.[39] Armia was sent back to Laval on 12 November.[40] After Arber Xhekaj was placed on injured reserve, the Canadiens recalled Armia on 24 November.[41] Armia ended up scoring 17 goals in the regular season, breaking his personal goal record.[42][43] The Canadiens chose Armia as their candidate for the Bill Masterton Memorial trophy.[44][45]
Following the 2021–22 NHL season, the Canadiens having failed the make the playoffs, Armia accepted an invitation to play for Finland national team at the senior level internationally for the first time at the 2022 IIHF World Championship, which was held in Finland. In his debut against Norway national team, he recorded a goal and an assist in Finland's 5–0 victory.[46] In his first nine games, Armia recorded four goals and three assists, including the game-winning goal in Finland's semifinal victory over United States national team to reach the championship final.[47] He scored his fifth goal of the tournament in Finland's 4–3 victory over Canada national team in the final, winning a gold medal.[48]
After the 2022 competition, Armia said that he would like to participate the following year. Armia accepted the invite for the 2023 IIHF World Championship.[49] He would score his first goal in the tournament against Germany national team in a 4–3 victory for Finland.[50] Armia's second goal and only assist came against Hungary national team in a 7–1 victory.[51] Finland lost to Canada national team in the quarterfinals.[52] Armia played eight games and recorded two goals and an assist for a total of three points.
Armia was born in Pori, Finland in 1993. Armia attended the Swedish-speaking school in Pori, the Björneborgs svenska samskola, in his youth. The school is known for having many talented ice hockey players as students.[53][54]