Eckhoff has been part of the Norwegian biathlon team since 2008. and in the
women's relay and gold in the
mixed relay together with
Tora Berger,
Ole Einar Bjørndalen and
Emil Hegle Svendsen. She is the sister of former biathlete
Stian Eckhoff and studied engineering at the
Norwegian Institute of Technology. In 2016, she became World Champion on 7.5 km sprint in her home arena, Holmenkollen, in Norway. She was also part of the Norwegian team who took the bronze medal in the mixed relay and played an instrumental part in the Norwegian women's relay gold medal, shooting 10/10 as the third skier. In the 19–20 season, she won seven World Cup races, but she finished second in the Overall, behind
Dorothea Wierer. She won her first-ever discipline title in pursuit. In the 20–21 season, she won 4 gold and took 6 medals in 7 races during the
Biathlon World Championships 2021. Later in the season, she won the
2020–21 World Cup overall title, winning the most races in a season since
Magdalena Forsberg. She also won the discipline title in sprint and pursuit, becoming the first male or female biathlete to win seven consecutive races in a discipline (sprint competition). She was awarded the
Holmenkollen Medal in 2022. Eckhoff did not participate in the
2022–23 Biathlon World Cup due to persistent health issues resulting from a Covid infection she contracted at the 2021/2022 end-of-season party. On March 15, 2023, she announced through her social media that she would not return to competition. Eckhoff later confirmed in a 2025 German television documentary on life after biathlon that long Covid and the powerful medications needed to treat her persistent sleep problems forced her retirement. This left her with "no formal education." "It was really a tough time." ==Biathlon results==