A former Zamboni driver, Niemi became the first Finland-born goalie to win the Stanley Cup. The native of Vantaa, Finland, earned that distinction in 2010, when he also placed his name alongside those of Ed Belfour and Tony Esposito in the Chicago Blackhawks record books.

With the Blackhawks' 2-0 victory against the Nashville Predators in Game 2 of the first round of the Stanley Cup Playoffs on April 18, 2010, Niemi became the first Blackhawks goalie to get a playoff shutout since Belfour in 1996. Two games later on April 22, Niemi did it again against Nashville, making him the first Chicago goalie to have two shutouts in the same playoff series since Esposito in 1974.

Starting all 22 games that postseason, Niemi went 16-6 with a 2.63 goals-against-average and a .910 save percentage to help the Blackhawks win the Cup, but his stay in Chicago was short-lived. He signed a free agent contract with the San Jose Sharks on Sept. 2, 2010.

Nicknamed "Nemo'' by his new teammates, Niemi went on to spend five seasons in San Jose. He helped the Sharks make the playoffs four times, ranking third in balloting for the Vezina Trophy, given to the NHL's best goalie, in 2012-13 and finishing 11th in voting for the Hart Trophy, awarded to the League's MVP, that season.

The Sharks traded Niemi to the Dallas Stars on June 27, 2015, for a 2015 seventh-round draft pick. Dallas signed Niemi, who was due to become an unrestricted free agent, to a three-year contract two days later and paired him with fellow Finnish goaltender Kari Lehtonen in 2015-16.

Niemi's Stars debut Oct. 8, 2015, was one to remember. In addition to stopping all 37 shots he faced, Niemi assisted on each of the Stars' first two goals in their 3-0 win against the Pittsburgh Penguins.

Niemi played 48 games during his first season in Dallas and went 25-13-7 with a 2.67 GAA and a .905 save percentage to help the Stars make the playoffs.