Carlsson (6-2, 194 pounds) had 25 points (10 goals, 15 assists) and seven power-play goals in 44 games in the Swedish Hockey League. The 18-year-old was named Swedish Junior Hockey Player of the Year after he led all under-19 players in the SHL in goals and points and tied for first in assists. Carlsson had six points (three goals, three assists) in seven games playing mostly on the wing for fourth-place Sweden at the 2023 IIHF World Junior Championship, and five points (three goals, two assists) in eight games playing center at the 2023 IIHF World Championship. Carlsson became the seventh Sweden-born player to be chosen among the top three in the NHL draft, joining Rasmus Dahlin (Buffalo Sabres, No. 1, 2018), Gabriel Landeskog (Colorado Avalanche, No. 2, 2011), Victor Hedman (Tampa Bay Lightning, No. 2, 2009), Daniel Sedin (Vancouver Canucks, No. 2, 1999), Henrik Sedin (Canucks, No. 3, 1999) and Mats Sundin (Quebec Nordiques, No. 1, 1989).