Thomsen arrived at Hayes Lane in the summer ahead of the 2026/27 season, from National Women’s Super League (NWSL) outfit Utah Royals FC and has previously played in Denmark and Norway. 

In her debut NWSL season, Thomsen made 26 appearances for Utah Royals, starting 20 matches and scoring three goals.

Primarily deployed at right-back, the 26-year-old quickly established herself as a key member of the squad in one of the world's most competitive women's leagues. She has featured 11 times during Utah’s current campaign.