The 19-year-old native of Solna, Sweden scored his first two professional goals for Leksands' senior team in 2021-22, totaling four points (2+2) in 28 contests. He also recorded nine points (4+5) in eight games for Leksands' Under-20 team during the campaign.
He made Sweden's roster for the 2022 IIHF World Junior Championship and played in the team's first two games before the tournament was postponed due to the COVID-19 pandemic.
Rosen also earned a bronze medal with Sweden at the 2021 IIHF U18 World Championship and tied for the team lead with nine points (7+2) in seven tournament games.