Krüger was announced as the first of four nominees for the 2009–10 Elitserien Rookie of the Year on 18 October 2009 after starting the season with five goals and 11 assists in just 13 games.

Krüger signed a three-year contract with the Chicago Blackhawks in June 2010, but opted to stay with Djurgården during the first year of the contract He was later recalled from Djurgården to Chicago on 23 March 2011. Krüger’s first full season with the Blackhawks was in 2011–12, when he played in 71 games with the club, scoring nine goals and adding 17 assists.

Krüger has represented Sweden three times in international play. At the junior level, he helped his country capture a bronze medal at the 2010 World Junior Championships. After graduating to the senior level, Krüger has played for Sweden twice, in 2011 (finishing with a silver medal) and 2012. He also represented Sweden in the 2014 Winter Olympics. After several injuries to the team’s centremen, Krüger played on Sweden’s first line in the tournament final against Canada, which the Swedes lost, 3–0.

On 9 April 2013, in Game 5 of the Western Conference Quarter-finals, Krüger scored his first career Stanley Cup playoff goal, which happened to be the game winner, against Minnesota Wild goaltender Josh Harding. The Blackhawks eventually won the 2013 Stanley Cup, with Krüger contributing three goals during the team’s run. After his playoff success with the team, Krüger signed a two-year extension with the Blackhawks on 12 July 2013.

He scored eight goals along with 20 assists in 81 games for Chicago during the 2013–14 NHL season. On 19 May 2015, he scored the game winning triple overtime away goal to tie the Western Conference finals 1–1 against the Anaheim Ducks.

On 11 September 2015 Krüger signed a one-year, 1.5 million dollar contract to stay with the Blackhawks for the 2015–16 season. On December 17, Krüger dislocated his wrist in a game against the Edmonton Oilers. He was projected to miss at-least four months while recovering from the injury. On 27 February 2016 the Blackhawks announced that Krüger would be switching his number to 22 in order for his new teammate acquired from the Winnipeg Jets, Andrew Ladd, to keep his traditional number 16. On March 9, The Blackhawks signed Krüger to a three-year, $9.25 million contract extension that runs through the 2018–19 season.

After completing his seventh season with the Blackhawks, Krüger was long rumoured as a candidate to be traded away due to considerable salary cap constraints. With a reported deal to the Vegas Golden Knights pre-dating the 2017 NHL Expansion Draft for draft considerations, Krüger surprisingly remained with Chicago through to the opening of free agency. On 2 July 2017, Krüger was dealt by the Blackhawks to the Golden Knights in exchange for future considerations. On 4 July 2017, Krüger was then moved on by the Golden Knights in a trade to the Carolina Hurricanes for a 5th-round pick in the 2018 NHL Entry Draft. Krüger was placed on injured reserve by the Hurricanes on 3 January 2018, and was placed on waivers on 8 February.

On 3 May, Krüger was initially traded by the Hurricanes to the Arizona Coyotes along with a third-round pick in the 2018 NHL Entry Draft, in exchange for forward Jordan Martinook and a fourth-round pick in the 2018 NHL Entry Draft. On 12 July 2018, Krüger was then traded by the Coyotes back to the Blackhawks along with prospect MacKenzie Entwistle, Jordan Maletta, and Andrew Campbell in a deal that sent the contract of Marián Hossa to the Coyotes, along with Vinnie Hinostroza, Jordan Oesterle and a third-round pick in the 2019 NHL Entry Draft.

Following the 2018–19 season, Krüger ended his nine-year career in the NHL, returning to Europe as a free agent in signing a two-year contract with Swiss club, ZSC Lions of the NL, on 5 July 2019.