Mittermüller, who competes for WSV Bischofswiesen , drove her first FIS World Cup race in November 2000 in Tignes , where she came 23rd in the halfpipe . At the beginning of the 2002/03 season she reached her first and so far only podium finish in the World Cup in Tandådalen with third place in the halfpipe competition. In the further course of the season Mittermüller took several top ten positions and thus reached seventh place in the halfpipe rating. At the Snowboard World Championships in 2003 on Kreischberg , she came in 32nd place in the halfpipe competition. In February 2003 she won the silver medal on the halfpipe at the 2003 Junior Snowboard World Championships in Prato Nevoso .
At the beginning of the 2008/09 season Mittermüller reached second place in the Slopestyle at the Horsefeathers Pleasure Jam in Schladming . This was followed by a win at the 2009 Burton Canadian Open in Calgary and third place at the X-Trail Asian Open in Bandai . She finished the season in sixth place in the World Snowboard Tour overall ranking. In the 2010/11 season, she finished third in the Big Air competition at Billabong Bro Down in Snow Park and second in slopestyle at the 2011 Burton Canadian Open in Calgary. In August 2011 she won the New Zealand Winter Games in Cardrona in Big Air.
At the start of the 2012/13 season, she won the slopestyle at The Mile High in Thredbo Resort . Another win at the Stylewars in Falls Creek followed . At the end of the season she reached fourth place in slopestyle at the Nescafé Champs in Leysin and ended the season in third place in the overall World Snowboard Tour ranking. In August 2014, she finished third in slopestyle at The Mile High in Perisher Blue . At the Snowboard World Championships 2015 on Kreischberg , she finished 14th in slopestyle and 11th in big air. After eighth place in slopestyle at the beginning of the 2015/16 season in Cardrona , she finished second and one at the European Cup in Landgraaf in slopestyle. In March 2016 she won her first World Cup victory in Slopestyle in Špindlerův Mlýn and at the end of the season she finished eighth in the Freestyle World Cup and third in the Slopestyle World Cup. In the following year she finished 15th in slopestyle and 11th in big air at the 2017 snowboard world championships in Sierra Nevada and third in slopestyle at the World Cup in Špindlerův Mlýn.
In 2018 Mittermüller tore a meniscus during her Olympic debut while training for the Slopestyle competition at Phoenix Snow Park in Bokwang , competed in the competition despite the injury and completed a rated run. When Big Air could not take more.
Germany
World cup
TTR World Snowboard Tour
