Carlsson originally played at the youth level with hometown team
Färjestad BK before moving to fellow tenured
Swedish Hockey League (SHL) team,
Örebro HK, for the 2020–21 season. During the
2021–22 season, Carlsson made his professional debut in the SHL as a 17-year-old, posting three goals and six assists in 35 regular-season games. In his year of
NHL draft eligibility, Carlsson increased his stock in playing exclusively with the senior team in the SHL showing an offensive acumen in securing a scoring line role among Örebro HK for the
2022–23 season.
Bob McKenzie referred to Carlsson as a "
blue-chip" prospect in the
2023 NHL entry draft. On 28 June 2023, Carlsson was drafted second overall by the
Anaheim Ducks in the 2023 draft. He signed a three-year, entry-level contract with the Ducks on 12 July. On 10 October, Carlsson was named to the Ducks' opening night roster for the
2023–24 season after attending the team's training camp. However, he suffered an injury during practice on 6 October, and was unable to play in the Ducks' first two games of the season. Carlsson made his NHL debut on 19 October, scoring a goal in the Ducks' 3–2 loss against the
Dallas Stars. On 10 November, in a 6–3 loss to the
Philadelphia Flyers, Carlsson became the youngest player in Ducks franchise history to record a
hat-trick, at 18 years and 319 days old. During a game against the
Boston Bruins on 22 February 2025, Carlsson tallied his 49th career point to tie
Hampus Lindholm for the fourth-most points by a Ducks player before age 21. ==International play==