He played ten seasons for the Minnesota Wild and Calgary Flames in the National Hockey League (NHL), during which he won both the William M. Jennings Trophy and Roger Crozier Saving Grace Award.

Bäckström won the 1998 World Junior Ice Hockey Championships as a backup goaltender for the Finnish national team, along with players like Olli Jokinen, Niklas Hagman, Mika Noronen, Niko Kapanen, Toni Dahlman and Eero Somervuori.

[3] Although he was initially expected to split his ice time with rookie Josh Harding, an unexpected injury made Bäckström the Wild's permanent backup for starting goaltender Manny Fernandez.

[8] After Fernandez suffered a knee injury on 30 January, Bäckström thrived as the main starter, posting an 8–2–1 record over 11 games.

[11] His outstanding play helped lift the Minnesota Wild to a 35–23–5 record and rank second in the Northwest standings with 75 points.

[9][12] However, shortly following this honor, Bäckström left the second period of a game against the Calgary Flames with a lower-body injury and was replaced by Harding.

[13] The injury did not force Bäckström out long term and he quickly returned as the Wild's starter for their game against the Boston Bruins a few days later.

After losing the first three games of the series, Bäckström made 28 saves to clinch his first career playoff win and stave off a four-game sweep.

[18] Ahead of the 2007–08 season, the Wild traded Fernandez to the Boston Bruins and signed Bäckström to a two-year $6.2-million contract extension.

[28] However, Bäckström failed to maintain the consistency he showed during his rookie season as he slumped during February and the Wild lost their first five games of March.

[30] Bäckström continued to be consistent as he made 26 saves to lead the Wild to their first Northwest Division title in franchise history on 3 April.

[32] Bäckström showed an immediate return to his prime form as he recorded his 15th career shutout to lead the Wild to four straight wins to start the season.

[36] Bäckström helped the Wild remain undefeated in regulation throughout October until he was replaced by Harding after the first period of a game against the Dallas Stars.

He beat the previous record of 147:54 before giving up a goal to Scott Hartnell in the second period of a game against the Philadelphia Flyers.

[41] Prior to the All-Star break, Bäckström had improved to 22 wins on the season while falling to fifth among league goaltenders in goals against with 2.22 and sixth in save percentage.

[46] After the Wild failed to qualify for the playoffs, the team replaced head coach Jacques Lemaire with Todd Richards and hired Chuck Fletcher as their new general manager ahead of the 2009–10 season.

[48] Bäckström's play began picking up through the month and he recorded his 100th career NHL win on 9 November against the Toronto Maple Leafs.

[60] Coach Todd Richards defended Bäckström's declining record of 26–23–8, .903 save percentage, and 2.72 GAA by calling out the play of the teams' defencemen.

"[61] Despite the Wild failing to quality for the 2010 Stanley Cup playoffs, Bäckström held the franchise record in wins and shutouts while ranking second in goals against and save percentage.

As a result of his consistent play, Bäckström was named to the 2011 NHL All-Star ballot alongside teammates Mikko Koivu and Marek Židlický.

[76] Due to Harding's strong play, Bäckström sat out numerous games before returning to the Wild's lineup on 9 November and leading them to their fifth straight win.

[83] He returned to the Wild lineup on 29 March where he made 25 saves against the Florida Panthers for his first win since late February against San Jose.

[85] Due to the 2012–13 NHL lockout, Bäckström agreed to join the Dynamo Minsk of the Kontinental Hockey League to start the season.

[87] Once the NHL resumed, Bäckström returned to form and retook his place as the Wild's starting goaltender while Harding adjusted to medication for multiple sclerosis.

[90] At the end of the month, Bäckström was recognized as the NHL's Third Star of the Week after he recorded three consecutive wins against the Calgary Flames, Arizona Coyotes, and Edmonton Oilers.

[97] While recovering from surgery, Bäckström signed a three-year, $10.25 million contract extension to remain with the Wild before becoming an unrestricted free agent.

However, during this game, he suffered an upper-body injury after he was elbowed by Toronto Maple Leafs centre Nazem Kadri in the first period.

[104] On 4 March, Bäckström was ruled out for the remainder of the season[105] and the Wild acquired goaltender Ilya Bryzgalov to serve as Kuemper's backup.

[110] As both Bäckström and Kuemper struggled to maintain consistency in net, the Wild acquired Devan Dubnyk from the Arizona Coyotes on 14 January 2015.

On 10 June 2016, Bäckström effectively ended his NHL career after signing, as an impending free agent, a one-year contract with former club HIFK in Finland.