Sundin competed in junior races until 2011. Since 2011 she has mainly competed in the Scandinavian Cup . She ran her first World Cup race in Gällivare at the end of November 2012 , which she finished with 57th place in the 10 km freestyle. In January 2013 she got her first World Cup points in Liberec with 19th place in the sprint. In the 2013/14 season she came in the Scandinavian Cup six times in the top ten, including second place in the 10 km mass start race in Otepää and finished eighth in the overall standings at the end of the season. Her best World Cup result so far was seventh in the sprint in Lahti in March 2014 . In the 2015/16 season she achieved six places in the top ten in the Scandinavian Cup. She took second place in Vuokatti over 10 km freestyle and at the end of the season she was 14th in the overall standings.
She has also been competing in the Rollerski World Cup since 2012 , where she has taken 21 podium positions and 11 victories so far (as of October 6, 2015). She won the overall roller ski world cup in 2012 and came second in 2015 . In 2014 she became the Swedish champion in rollerskiing over the short distance. In September 2015 she won the silver medal in the 10 km mountain run at the roller ski world championships in Val di Fiemme and the gold medal in the team sprint together with Linn Sömskar and in the 19 km mass start race.
Sweden
Tripoli
Toblach
Oroslavje