When the Florida Panthers selected Markstrom in the second round (No. 31) of the 2008 NHL Draft, they were convinced he could not only be a starter, but a star in the NHL.

Markstrom had the size scouts dream of, and he had great intuition and reflexes. Two seasons later he led the Swedish Hockey League in goals-against average (2.01) and save percentage (.927).

Between the 2017-18 and 2022-23 seasons, Markstrom played 72 percent of his team's total games (327 of 453) and had a 2.66 GAA and .911 save percentage over that span. He signed a six-year, $36 million contract with the Calgary Flames on Oct. 9, 2020, and won 37 games with a 2.22 GAA and 922 save percentage and led the NHL with nine shutouts in 2021-22 to finish second in Vezina Trophy voting.

Markstrom was traded to the New Jersey Devils by the Flames for a first-round pick in the 2025 NHL Draft and defenseman Kevin Bahl on June 19, 2024. He ranked fourth since 2019-20 in games played (256), fourth (tied) in shutouts (17), sixth in saves/shots against (6,594/7,256), and sixth in wins (138) at the time of the deal. He signed a two-year, $12 million contract (average annual value of $6 million) with the Devils on Oct. 31, 2025, and was named to Team Sweden's roster for the Olympic Winter Games Milano Cortina 2026.

The Panthers signed Markstrom to an entry-level contract June 1, 2010 and he made his NHL debut against the Devils on Jan. 23, 2011, replacing starter Scott Clemmensen at the start of the second period. After one game, Markstrom was sent to Rochester of the American Hockey League to gain experience but injured his knee and needed surgery.

Over the next three seasons, the goalie many considered the best playing outside the NHL, playing 46 games for the Panthers while putting up encouraging numbers for San Antonio of the AHL. He was traded to the Vancouver Canucks by the Panthers on March 4, 2014.

In Vancouver, the surroundings were new, but the challenges were very familiar. After failing to unseat Eddie Lack as No. 2 to veteran Ryan Miller, Markstrom was back in the AHL again, this time with Utica. But the Canucks traded Lack to the Carolina Hurricanes on June 27, 2015, which gave Markstrom an opportunity.

In 2015-16 he played 33 games for the Canucks, winning 13, and had a 2.73 GAA and .915 save percentage. Markstrom won 23 games for the Canucks in 2017-18, then improved to 28 in 2018-19. He was named to his first NHL All-Star Game on Jan. 3, 2020, replacing Vegas Golden Knights goalie Marc-Andre Fleury.

At the 2009 IIHF World Junior Championship, Markstrom helped Sweden finish first. He had a 1.61 GAA and .943 save percentage and was named the tournament's top goalie.