Thorsnes was born in
Leikanger Municipality. She made her debut for the former elite team
Kaupanger, and stayed there until her debut for
Arna-Bjørnar in 2006. Thorsnes made her debut at the same time as
Erika Skarbø,
Madeleine Giske and
Trude Johannessen. Arna-Bjørnar finished in 5th place in 2006. Thorsnes was the top scorer in the Toppserien with 19 goals, and was named Young Player of the Year, and was named to the 2006 Toppserien Team of the Year. The 2007 season was less successful for Thorsnes as she only scored 6 goals and Arna-Bjørnar finished in 4th place. In the 2008 season Thorsnes scored 14 goals in the Toppserien, she also scored 11 cup goals in 10 cup games. She helped
Arna-Bjørnar to a 5th-place finish and scored against all the top teams (apart from Røa). On 12 December, Thorsnes revealed that she would be signing with
Røa. Thorsnes won two championships in her first three seasons in Røa. In 2011, she was the Toppserien's Golden Boot for the second time with 27 goals, a personal record. Following the 2012 season, Thorsnes signed with
Stabæk. In the 2013 season Thorsnes won the Golden Boot for the third time, scoring 19 goals. Stabæk finished in first place in the
Toppserien and won the
Norwegian Cup. After two seasons with
Stabæk, Thorsnes joined
Avaldsnes where she would play for three seasons. In 2017 Thorsnes became the all-time leading goal scorer in the Toppserien. In October 2017, Thorsnes joined
Canberra United for the
2017–18 W-League season, meaning she would play club football outside of Norway for the first time. Thorsnes scored six goals in nine games with Canberra. On 14 February 2018 Thorsnes signed with the
Utah Royals of the
NWSL for their inaugural season. This was a disappointing stint for Thorsnes as she only appeared in nine games, and didn't score any goals. After the season ended Utah declined her contract option, she was placed on Re-Enty wires and wasn't claimed by another team. In November 2018, Thorsnes signed a one-year contract with Toppserien Champions
LSK Kvinner for the 2019 season. In 2019 Thorsnes went to
Canberra United as a guest player for the season, after she is finished there she is going back to her former club
Avaldsnes. ==International career==