Born in Örebro, Sweden, Fahlin competed at the 2012 Summer Olympics in London during the women's road race, finishing 19th, and in the women's time trial, finishing 17th. At the 2016 Summer Olympics in Rio de Janeiro, she finished 27th in the Women's road race. Two weeks later, in late-August 2016, she won her first World Tour race, the Open de Suède Vårgårda in Sweden.