Karlsson, who competes for Sollefteå SK , appeared internationally for the first time in January 2017 at the Nordic Junior World Ski Championships in Soldier Hollow . There she finished 23rd in the sprint and fifth in the relay. In March 2017 she became Swedish junior champion over 5 km classic and 10 km freestyle in Kalix . At the Nordic Junior World Ski Championships in Goms in 2018 , she won the bronze medal in the sprint and relay and the gold medal in the skiathlon . In addition, she came in seventh place over 5 km classic. In February 2018 she became the Swedish junior champion in Jönköping in sprint, over 15 km classic and 5 km freestyle. In the same month she ran her first race in the Scandinavian Cup on the mini tour in Trondheim . She achieved 16th place in the sprint, second place over 5 km classic and achieved third place in the tour ranking with the third fastest time on the final stage.
In the 2018/19 season, Karlsson won over 10 km classic and in the 20 km mass start race in Vuokatti in the Scandinavian Cup and thus achieved tenth place in the overall ranking of the Scandinavian Cup. At the Nordic Junior World Ski Championships in Lahti in 2019 , she won the bronze medal in the relay and the gold medal in the 5 km freestyle and in the 15 km mass start race. In addition, she was fifth there in the sprint. She made her debut in the World Cup in February 2019 in Cogne . There she got her first World Cup points with the seventh place over 10 km. A few days later she won the silver medal on this route at the 2019 World Championships in Seefeld in Tyrol . She won the gold medal in the women's relay and the bronze medal in the final 30 km freestyle race. At the World Cup final in Québec she was ninth and finally reached 40th place in the overall World Cup. After finishing eighth in the Ruka Triple at the beginning of the 2019/20 season, she did not take part in the World Cup ski tour until February 2020. She finished 19th in Östersund over 10 km freestyle and in the subsequent pursuit, where she ran the second fastest time, 13th place. In March 2020 she finished third with the relay in Lahti and won her first World Cup victory in the 30 km mass start race on Holmenkollen .
Sweden
Oslo
Vuokatti
