Agreiter participated in junior races until 2011. She ran her first World Cup race in March 2011 in Lahti , which she finished with 53rd place in the skiathlon . She got her first World Cup points in November 2011 in Sjusjøen with the 26th place in the sprint. At the U23 World Championships 2012 in Erzurum , she won silver in the 15 km skiathlon. In December 2012 she achieved her best individual World Cup result so far in Canmore with 13th place in the skiathlon. At the Tour de Ski 2012/13 she finished 22nd. Her best placings at the Nordic World Ski Championships 2013 in Val di Fiemme were 16th place over 10 km freestyle and eighth place with the relay. At the U23 World Championships in Liberec in 2013 , she won silver in the 15 km skiathlon and bronze in the 10 km freestyle. She finished the season in 46th place in the overall World Cup ranking. She finished the Tour de Ski 2013/14 in 25th place. At the 2014 Winter Olympics in Sochi , she finished 30th in the 15 km skiathlon and 16th in the 30 km mass start race. In the 2014/15 and 2015/16 seasons, she mainly started in the cross-country Alpine Cup . She achieved two second places and one victory. At the Tour de Ski 2016 , she finished 38th. At the end of the 2015/16 season, she came eighth in the overall ranking of the Alpine Cup.