Education
In 2011-2012 Karlsson finished 12th in Allsvenskan in points with 45 points in 46 games, and was second on his team (Broc Little led the league in points).
In 2011-2012 Karlsson finished 12th in Allsvenskan in points with 45 points in 46 games, and was second on his team (Broc Little led the league in points).
He was drafted in the second round, 53rd overall, by the Anaheim Ducks in the 2011 National Hockey League Entry Draft. He made his senior Swedish Hockey League debut with HV71. On 20 May 2013, Karlsson was signed by the Ducks to a three-year entry level contract.
He was returned on loan to HV71 for the 2013-2014 season.
Karlsson scored his first and second National Hockey League goals on 13 October 2014, against Michal Neuvirth of the Buffalo Sabres. On 2 March 2015, Karlsson was traded by the Ducks to the Columbus Blue Jackets along with Rene Bourque, and a 2015 second round pick for James Wisniewski and a 2015 third round pick.