Nilsson participated in junior competitions until 2012. At the European Youth Olympic Winter Festival 2011 , she won the sprint competition. At the Swedish Junior Championships in 2010 and 2011, she won gold in the sprint. In the 2011/12 season she took part in the Scandinavian Cup , where she won two sprint competitions. At the Nordic Junior World Ski Championships in 2012 in Erzurum , she won gold in the sprint and silver in the relay. She had her first World Cup race in Drammen in March 2012 . In the sprint competition, she took 23rd place and thus got her first World Cup points. In the first half of the 2012/13 season she took part in the Scandinavian Cup. After good results, she was allowed to take part in the World Cup again in Liberec in 2013 . She took second place in the team sprint together with Ida Ingemarsdotter . At the Nordic Junior World Ski Championships 2013 in Liberec, she won gold in the sprint and relay. At the Nordic World Ski Championships in 2013 in Val di Fiemme , she reached fifth place in the sprint. She ended the 2013/14 season with 12th place in the Sprint World Cup. In March 2014, she achieved her first podium in the World Cup with third place in the sprint. At the 2014 Winter Olympics in Sochi , she won bronze in the team sprint together with Ida Ingemarsdotter. In the sprint competition she reached 10th place.
At the beginning of the 2014/15 season , Nilsson finished 21st at the Nordic Opening in Lillehammer . At the World Cup sprint in Davos , she achieved second place. This was followed by further podium finishes in Otepää with second place in the sprint and a victory in the team sprint and a third place in the sprint in Östersund . At the Nordic World Ski Championships in Falun in 2015 , she won silver in the sprint, in the team sprint together with Ida Ingemarsdotter and with the relay. She finished the season in 12th place in the overall World Cup, in fourth place in the sprint classification and in first place in the U23 classification. At the beginning of the 2015/16 season she took second place at the Nordic Opening in Ruka . She came second in the sprint and the final stage. This was followed by a World Cup victory in the sprint in Davos and a third place in the sprint in Toblach . She finished the 2016 Tour de Ski in 24th place. Her best placings were two sixth places in sprints in Lenzerheide and Oberstdorf . At the following World Cup in Planica she won the sprint and together with Ida Ingemarsdotter in the team sprint. In February 2016 she came on the podium again with third place in the sprint in Stockholm . In the Ski Tour Canada , which she ended prematurely, she finished second in the sprint stage in Gatineau and won the sprint stage in Quebec . She finished the season in 11th place in the overall World Cup, in third place in the Sprint World Cup and, as in the previous year, in first place in the U23 classification.
At the first World Cup station of the 2016/17 season in Ruka , Nilsson took her fourth World Cup victory in the sprint. This was followed by fifth place in the World Cup mini tour in Lillehammer . At the World Cup in La Clusaz , she was third with the relay. She finished the Tour de Ski 2016/17 with four stage wins in third place. In January 2017, she won the Falun sprint . She also won the following sprint world cups in Otepää and Drammen . At the beginning of February 2017 she finished second in the skiathlon at the Swedish championships. At the season highlight, the Nordic World Ski Championships 2017 in Lahti , she won the silver medal with the relay. She also took 26th place in the skiathlon, 13th place over 10 km classic and 12th place in sprint. At the end of the season she came third in the overall standings at the World Cup finals in Québec . She won the sprint stage and came third in the final stage. She finished the season in sixth place in the Distance World Cup, fourth in the overall World Cup and second in the Sprint World Cup. At the beginning of the 2017/18 season, she won the sprint stage at the Ruka Triple and finished seventh overall. This was followed by further victories in the sprint in Davos and in Planica and a second place in Dresden together with Hanna Falk in the team sprint. At the 2018 Winter Olympics in Pyeongchang , she won the bronze medal in the 30 km mass start race, the silver medal with the relay and together with Charlotte Kalla in the team sprint and the gold medal in the sprint. At the end of the season she was second in the sprint in Lahti and Drammen and reached 12th place in the overall World Cup and second place in the Sprint World Cup. At the end of March 2018 she became the Swedish sprint champion in Skellefteå .
After finishing second in the sprint at the Lillehammer Tour, which she finished in sixth place at the beginning of the 2018/19 season, Nilsson won five individual sprint races and the team sprint in Dresden together with Maja Dahlqvist . At the season highlight, the Nordic World Ski Championships 2019 in Seefeld in Tirol , she won the silver medal in the sprint and the gold medal in the team sprint together with Maja Dahlqvist and the relay. At the World Cup finals in Quebec, she won the classic overall standings with victories in the sprint and the mass start race over 10 km and finally achieved fifth place in the overall World Cup and first place in the Sprint World Cup. At the beginning of April 2019 she became Swedish champion in the team sprint together with Anna Dyvik .
In the summer of 2019, Nilsson broke his rib in preparation for the 2019/20 season and had to take a break for several weeks. Nevertheless, she reached the finals in every sprint at the beginning of the season and came second in both the individual and team sprints in Planica . She broke off the Tour de Ski after the first stage due to renewed pain in the rib area. Eventually a stress fracture was diagnosed and Nilsson decided to end her season in February 2020.
biathlon
At the end of March 2020, Stina Nilsson announced that she would switch to biathlon for the 2020/21 season. She was immediately accepted into the A team and trained with them in Östersund .
Participation in World Championships and Olympic Winter Games
Olympic games
2014 Sochi : 3rd place team sprint classic, 10th place sprint freestyle
2018 Pyeongchang : 1st place sprint classic, 2nd place 10 km freestyle, 2nd place team sprint freestyle, 2nd place relay, 3rd place 30 km classic mass start, 10th place 15 km skiathlon