At the beginning of the 2006–07 season, Bäckström was the backup for the Wild's starting goaltender, Manny Fernandez. He made his NHL debut on 7 October 2006, notching his first career win in a 6–5 victory over the Nashville Predators. In his seventh career game, Bäckström continued to impress in recording his first career shutout in a 4–0 victory over the Phoenix Coyotes on 24 November 2006. After Fernandez suffered a knee injury mid-season, Bäckström was forced into the starter's position. He played exceptionally well over the second half of the season, finishing first in the NHL in both goals against average and save percentage, while tying Dwayne Roloson's team record with 5 shutouts in just 36 starts. Upon the trade of Fernandez to the Boston Bruins in 2007, Bäckström became Minnesota's starting goaltender. He recorded 33 wins in the 2007–08 season and was the starter for Minnesota's first round Stanley Cup playoff series against the Colorado Avalanche, which Colorado won in six games. Though he was due to become an unrestricted free agent on 1 July 2009, Bäckström signed a four-year, $24 million contract on 3 March2009, to remain with the Wild. Despite Bäckström's 37 wins and strong goaltending, the Wild ultimately did not qualify for the playoffs in 2009. In that season, Bäckström finished as the runner-up for the Vezina Trophy, awarded to the NHL's top goaltender. In 2012, Bäckström played very well in the first half the season and the Wild had a chance to make the playoffs. However, in the second half of the season, Bäckström slumped and suffered injuries as the Wild failed to make the playoffs. In the following seasons, Bäckström played on-and-off with the additions of goaltenders Ilya Bryzgalov, Darcy Kuemper and Devan Dubnyk to the Wild. In the 2015–16 season, he was often a healthy scratch as Kuemper dressed as Dubnyk's backup.
Calgary Flames
Having yet to appear in a competitive game with the Wild in the 2015–16 season, on 29 February 2016, Bäckström was traded to the Calgary Flames in exchange for forward David Jones. He appeared in four games for the Flames, recording two wins.
Return to Finland
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. In May 2018, Bäckström signed a one-year contract with Tappara.
Personal life
Bäckström is married to wife Heidi. The couple have two children: Benjamin and Isabella.
