Amateur

During the 2005–06 season, Stålberg played for Frölunda HC in the J20 SuperElit. He led the team in scoring with 33 goals and 31 assists in 48 games during the regular season and playoffs.^[1] After this season, Stålberg was drafted by the Toronto Maple Leafs in the 6th round (161st overall) of the 2006 NHL Entry Draft.^[2]

Stålberg joined the University of Vermont, hitting the ice for his freshman season in 2006–07.^[1] He was one of only two freshmen on the team who played in all 39 of the club's games that season.^[1] He finished the season with 7 goals and 8 assists for 15 points.^[2] During the season, he was named Hockey East Rookie of the Week on 13 November 2006, as well as being named to the Hockey East Weekly Honor Roll.^[1] At the end of the season, Stålberg was named to the Hockey East All-Academic Team.^[1]

During his sophomore season in 2007–08, Stålberg again played in all 39 games for the Catamounts, scoring 10 goals and adding 13 assists.^[2] During the year, he was named Hockey East Player of the Week three times, and was also named to the Hockey East Weekly Honor Roll three times.^[1] At the end of the season, he was an honorable mention Hockey East All-Star and had earned a spot on the Hockey East All-Academic Team.^[1]

During his junior year at Vermont, Stålberg again played in 39 games, scoring 24 goals and adding 22 assists.^[2] His 24 goals ranked fourth in the nation, and he led Vermont in points.^[1] He garnered many individual honors during this season. He was one of the ten finalists for the Hobey Baker Memorial Award. He was the first player from the University of Vermont to be a finalist for the award since Martin St. Louis.^[3] He was the fourth player in program history to be named a finalist for the Hobey Baker award after Kirk McCaskill '83 (1982), Eric Perrin '97 (1996) and Martin St. Louis '97 (1995, 1996, 1997). He was named the Hockey East Player of the Month for January, and picked up two Hockey East Player of the Week honors.^[1] During this year he and his teammates made it to the Frozen Four. Stalberg was also named a Division I First-Team All-American in 2008-09.

Professional

After his successful junior campaign at the University of Vermont, Stålberg decided to turn pro, signing a two-year, entry-level contract with the Maple Leafs on 14 April 2009.^[4] Immediately after signing his contract, Stålberg was assigned to the Toronto Marlies of the American Hockey League. He made his professional debut with the Marlies during the 2008–09 AHL playoffs.^[4]

Stålberg made his NHL debut in the 2009–10 season opener on 1 October 2009 in a 4-3 OT loss to the Montreal Canadiens.^[5] In that game, Stålberg recorded his first career assist and point with an assist on a goal scored by Matt Stajan.^[6] On 18 December 2009, Stålberg recorded his first NHL goal in a 5–2 loss to the Buffalo Sabres against Sabres goaltender Ryan Miller.^[7] Stålberg finished his rookie season playing in 40 games with 14 points recorded (9 goals, 5 assists).

On 30 June 2010, Stålberg was traded along with prospects Philippe Paradis and Chris DiDomenico to the Chicago Blackhawks in exchange for Kris Versteeg and Bill Sweatt.

On 15 December 2010, Stålberg suffered a concussion in a 4–3 loss against the Colorado Avalanche afer getting hit by Avalanche defenseman Ryan O'Byrne that led to Stålberg missing the next three games.^[8] On 2 March 2011, Stålberg played his 100th NHL game in a 6–4 win over the Calgary Flames, which saw him get into his first NHL fighting major after a fight against Flames defenseman Mark Giordano.^[9] Stålberg finished the 2010–11 season, his first season with the Blackhawks and second season in the NHL altogether with 12 goals, 12 assists for 24 points in 77 games. After the Blackhawks narrowly made the playoffs as the eighth seed in the Western Conference, Stålberg made his Stanley Cup playoff debut on 13 April 2011 in game 1 of the Blackhawks first round series against the Presidents' Trophy-winning Vancouver Canucks and scored his first career playoff goal two days later in game two on Canucks goaltender Roberto Luongo.^[10]

Stålberg recorded his first career hat trick on 10 January 2012 against the Columbus Blue Jackets.^[11] He finished the 2011–12 season with career highs in games played (79), goals (22), assists (21) and points (43). In game two of the first round of the 2012 Stanley Cup playoffs against the Phoenix Coyotes on 14 April 2012, Stålberg recorded his first career playoff assist on a goal scored by Bryan Bickell.

Stålberg won the Stanley Cup in 2013 as a member of the Blackhawks after they defeated the Boston Bruins in the 2013 Stanley Cup Finals in six games.

On the back of his success in the post-season with the Blackhawks, Stålberg signed a four-year deal worth $12 million with the Nashville Predators on 5 July 2013. He ended the 2013–14 season playing in 70 games with 8 goals, 10 assists for 18 points.

In the 2014–15 season, his second season with the Predators and sixth in the NHL, failing to live up to the expectations of his contract, Stålberg was demoted to AHL affiliate, the Milwaukee Admirals for portions the 2014–15 season. He was however summoned back to the Predators towards the end of the 2014-15 season and for the 2015 Stanley Cup playoffs in which the Predators lost in the first round in six games to Stålberg’s former team and the eventual Stanley Cup champion Chicago Blackhawks.^[12] On 30 June 2015, after he was placed on unconditional waivers, Stålberg was bought out from the remaining two-years of his contract with the Predators and released to free agency.^[13]

On 1 July 2015, with ambition to reclaim his status in the NHL, Stålberg was signed to a one-year contract with the New York Rangers.^[14] Having made the Rangers opening night roster for the 2015–16 season and despite an early season concussion on 24 October 2015 against the Philadelphia Flyers, Stålberg enjoyed early offensive success, securing a role on the checking line as the season went on.^[15] In 75 games with the Rangers, Stålberg contributed with 9 goals, 11 assists and 20 points.

On 1 July 2016, Stålberg left the Rangers as a free agent, agreeing to a one-year deal with the Carolina Hurricanes.^[16] In the 2016–17 season, after recording 12 points in 57 contests with the Hurricanes, who were out of playoff contention, Stålberg was traded to the Ottawa Senators in exchange for a 2017 third-round draft choice on 28 February 2017.^[17]

On 11 July 2017, Stålberg left the NHL as a free agent after eight seasons and agreed to a two-year contract with EV Zug of the National League (NL).^[18] He instantly became an impact player in Switzerland, collecting 22 goals and 50 points in 48 games and in the 2017–18 season. Placing fourth in league points, Stalberg also earned selection to the NL Media All-Star Team and named as the NL Media's Best Forward.

In the following 2018–19 season, Stålberg appeared in just 10 games before receiving and accepting a contract offer for the remainder of the year to leave Zug and move to the KHL with Avangard Omsk on 30 October 2018.^[19]

On 26 April 2019, Stålberg returned to Switzerland and agreed to a two-year contract through the 2020–21 season with HC Fribourg-Gottéron.^{[citation needed]}

On 13 August 2021, Stålberg announced his retirement from professional ice hockey.^[20]

Regular season and playoffs

International