2010-11: Anton Karlsson appeared in four games with the Frolunda U18 team as a 14-year-old and played for Goteborg 2 in the annual TV-Pucken tournament for Swedish high school age players. He had 1 assist with the Frolunda U18 team. Karlsson scored 7 goals with 1 assist in eight TV-Pucken games.
2011-12: Karlsson spent most of the year with Frolunda’s U18 team and played for Sweden’s U16 and U17 teams in international play as well as skating for Goteborg in the TV-Pucken tournament. Karlsson scored 12 goals with 19 assists in 28 U18 games and was +20 with 32 penalty minutes. Frolunda won the U18 bronze medal. In three matches with Sweden’s U17 team Karlsson scored 2 goals with 1 assist and he scored 2 goals with 6 assists in eight games with Sweden’s U16 team. He scored 6 goals with 6 assists in eight TV-Pucken games.
2012-13: Karlsson played for Sweden’s U18 team in the 2013 Ivan Hlinka Memorial Tournament in August before returning to Frolunda — where he split the season between the U20 and U18 squads. He later represented Sweden in the 2013 U17 World Hockey Challenge, where he was the team captain, and at the 2013 U18 World Junior Championship. He played 20 games in Sweden’s SuperElit U20 league, including three playoff games, and scored 5 goals with 5 assists; finishing +7 with 4 penalty minutes. In 23 games for Frolunda’s U18 team he scored 20 goals with 19 assists and was +12 with 64 penalty minutes. In three U18 playoff games he scored 1 goal with 3 assists and was +2. Karlsson had 2 assists and was +3 in five games at the Ivan Hlinka Tournament and was an assistant captain for the U18 team at the WJC. He scored 2 goals with 2 assists and was +3 with 10 penalty minutes in five games at that tournament. Sweden’s U17 team won the gold medal at the WHC and Karlsson scored 6 goals with 3 assists and 22 penalty minutes in six games. He was selected by Lokomotiv Yaroslavl in the fifth round (164th overall) in the 2013 KHL Draft.
2013-14: Karlsson played nine games at the men’s level in Sweden’s Allsvensan as a 17-year-old, playing for Mora IK on loan from Frolunda. He skated for Frolunda in the U20 SuperElit League and was with the club’s U18 team during its bronze medal playoff run. Karlsson played for the Sweden U20 and U18 teams in their respective world championship tournaments and skated for the Sweden U18 team in his second straight Ivan Hlinka Tournament. He was -3 with no points and 2 penalty minutes in AllSvenskan play. Karlsson scored 12 goals with 10 assists and was +3 with 88 penalty minutes in 28 games for the first-place Frolunda U20 team. Karlsson had an even plus/minus with 2 assists and 2 penalty minutes in three playoff games as Orebro shocked Frolunda in a best-of-three series. He scored 2 goals with 5 assists in five regular season games for the Frolunda U18 team and scored 3 goals with 3 assists, finishing +2 with 2 penalty minutes in five U18 playoff games. Karlsson was +1 with no points nor penalties in five games at the WJC with the Sweden U20 team. The squad won a silver medal, falling to Finland, 3-2 in overtime, in the gold medal game. Karlsson was -2 with no points and 4 penalty minutes in seven games for the Sweden U18 team that finished fourth at the WJC; falling to Canada, 3-1, in the bronze medal game. Serving as a team captain for Sweden’s seventh-place squad at the Ivan Hlinka Tournament, Karlsson scored 1 goal with 4 assists in four games. He was ranked 11th amongst international skaters in the Central Scouting final rankings and was selected by Arizona in the 3rd round (87th overall) in the 2014 NHL Draft. Karlsson was selected by Erie in the first round (55th overall) in the 2014 CHL Import Draft.
2014-15: Karlsson began the year with Skelleftea before returning to Frolunda at the end of November and played for the Sweden U20 team at the 2015 World Junior Champiionship. He skated in six regular season games and five Champions League contests for the Skelleftea men’s team, finishing -1 with 1 assist and 29 penalty minutes. Karlsson played nine SHL games for Frolunda and was -2 with 1 assist and 2 penalty minutes. He skated in 32 regular season games in the Sweden SuperElit league between the two clubs, scoring 14 goals with 15 assists, and was +3 with 41 penalty minutes. Frolunda captured a silver medal in the playoffs. Karlsson scored 3 goals with 7 assists and was +5 with 6 penalty minutes in eight playoff games. In seven games for Sweden at the WJC he was +1 with 2 assists and 6 penalty minutes. Sweden finished fourth, falling 4-2 to Slovakia in the bronze medal game.
Karlsson has limited offensive upside but is a pest and has been a fan-favorite wherever he has gone. He has been a point-per-game player at the junior level and will need to bring some of that upside to Frolunda’s senior team if he is to spend the full year there.
Karlsson skated in the Coyotes' prospect camp in July and was in Lake Placid with the Sweden U20 team over the summer. After spurning the Erie Otters of the OHL in favor of staying close to home, Karlsson has skated for Frolunda in Champions League play and will try to secure a spot on the club's SHL roster on a full-time basis in 2015-16. He is a candidate to play in his third World Juniors, which will take place in neighboring Finland. Whether Karlsson's decision to stay in Sweden reflects a lack of interest in playing in North America or a desire to compete at the men's level remains to be seen. Long-range he projects as a two-way forward with prototypical size and the demeanor to be successful in tight areas.