Carlsson, a defenseman from Gavle, Sweden, was selected by the Chicago Blackhawks in the fourth round (No. 110) of the 2016 NHL Draft after his second season with Brynas of the Swedish Hockey League. He played two more seasons with Brynas before signing an entry-level contract with the Blackhawks on May 21, 2018.
The Blackhawks assigned Carlsson to Rockford of the American Hockey League, where he scored nine goals and 33 points in 69 games of the 2018-19 season. He was sent back to Rockford to start 2019-20 before he was called up Feb. 22, 2020. He made his NHL debut at the Dallas Stars the next night and scored his first NHL point, an assist, against the Anaheim Ducks on March 3.