Maatta, who has won the Stanley Cup, earned an Olympic medal and been treated for cancer, has overcome challenges on and off the ice.

Maatta (6-foot-2, 206 pounds) was selected by the Pittsburgh Penguins with the No. 22 pick in the 2012 NHL Draft. He had just completed his first season in North America, helping London of the Ontario Hockey League reach the Memorial Cup championship game.

By the time Maatta debuted in the NHL as a 19-year-old in 2013-14, he had made two Memorial Cup appearances and played for Finland at the World Junior Championship. After a strong rookie season with the Penguins when he had nine goals and 29 points in 78 games, he seemed well on his way to becoming a top-pair, two-way defenseman, finishing fifth in Calder Trophy voting. He also won a bronze medal with Finland at the 2014 Olympics in Sochi before helping the Penguins reach the second round of the playoffs.

After having offseason shoulder surgery in May 2014, Maatta opened the 2014-15 season strong despite missing a good portion of training camp and every preseason game. He appeared set for an expanded role after getting three assists in the season opener.

But on Oct. 27, 2014, the Penguins announced Maatta had been diagnosed with low-grade thyroid cancer that would require surgery. Maatta continued to play before undergoing surgery, appearing in three more games before having the procedure Nov. 4.

Maatta was back on the ice two weeks later. After 10 more games, however, Maatta reinjured the same shoulder that required surgery earlier in the year. While on injured reserve, Maatta was diagnosed with mumps before it was determined he required a second surgery on the shoulder, which ended his season after 20 games.

Following a second summer of recovering from surgery, Maatta returned to the Penguins in 2015-16 healthy for the first time since his rookie season and helped Pittsburgh win the Stanley Cup.

Maatta, who scored seven points in 55 regular-season games in 2016-17, had eight points in 25 postseason games to help the Penguins win a second straight championship.

He played 142 games for Pittsburgh over the next two seasons before being traded to the Chicago Blackhawks on June 15, 2019,

Maatta signed a one-year, $2.25 million contract with the Detroit Red Wings on July 14, 2022. He had 17 points (five goals, 12 assists) and averaged 18:11 of ice time in 49 games before the Red Wings gave him a two-year, $6 million contract Feb. 16, 2023.

Maatta was traded to the Utah Hockey Club on Oct. 29, 2024, for a third-round pick in the 2025 NHL Draft and played for Finland at the 4 Nations Face-Off, where he led its defensemen in scoring (two assists in three games). He signed a three-year contract with Utah on March 3, 2025, helped Team Finland win bronze at the Olympic Winter Games Milano Cortina 2026, and was traded to the Calgary Flames on March 4, 2026.