2008-09: Johan Larsson played mostly for Brynas at the J20 junior level. In 33 games, Larsson scored 4 goals and added 5 assists for 9 points. He registered no points in 5 playoff games.
2009-10: Larsson played for the Brynas J20 squad once again, netting 15 goals and adding 19 assists for 34 points in 40 games. Larsson broke loose at the U-18 World Junior Championships in Minsk, posting 6 goals and 8 assists for 14 points in just 5 games, which ranked him second in points at the tournament. Larsson was also captain of the Swedish entry, which won silver. Larsson was chosen by the Minnesota Wild in the second round, 56th overall, of the 2010 NHL Draft.
2010-11: Larsson appeared in 43 games for Brynas as an 18-year-old rookie in Sweden's Elitserien and scored 4 goals with 4 assists. In mostly lower line duty, Larsson was +3 with 18 PMs as Brynas finished seventh in the 12-team league. He skated in all five playoff games and had 2 assists and was -4. In ten games with Brynas' U20 team he scored 6 goals with 9 assists. Larsson skated for Sweden at the 2011 U20 World Championship; scoring 1 goal with 3 assists and finishing with an even plus/minus in six games as Sweden finished fourth.
2011-12: In his second pro season with Brynas, Larsson won both a Swedish Elitserien championship and a gold medal at the 2012 U20 World Junior Championship. Larsson was Brynas' third-leading scorer during the regular season – scoring 12 goals with 24 assists in 49 games. Averaging 18:27 minutes per game, he was minus-ten with 34 penalty minutes. Brynas finished fourth during the season before its successful playoff run. Larsson scored 2 goals with 8 assists and was plus-six with 16 penalty minutes in 16 playoff games as Brynas captured the league title. He had 6 assists and was plus-three in six games for Sweden at the WJC. Sweden defeated Russia, 1-0, in overtime in the gold medal game.
Known as a hard-working, two-way player with a good eye for the game.
ISS: "Known as a very strong two-way player who has the ability to chip in offensively here and there...Larsson is a great team player who can do everything in every situation ..."
Larsson is likely to play in North America this season, and could probably stand a year of AHL seasoning.
Larsson was dealt by the Minnesota Wild to the Buffalo Sabres at the 2013 NHL trade deadline in the deal that sent Jason Pominville to the Wild.