Mugnier comes from Les Gets and started in FIS races for the first time in the 2007/2008 season after reaching the age limit . One month after her first European Cup race , she took part in the European Youth Olympic Festival in Szczyrk in February 2009 , where she won the silver medal in the giant slalom behind the Austrian Mirjam Puchner . In the following four years, Mugnier competed in the Junior World Championships . In 2012 she won the bronze medal in giant slalom in Roccaraso , and in 2013 another bronze medal in slalom. From the 2009/2010 season, Mugnier was regularly used in the European Cup. After several top 10 placements in winter 2010/2011, she achieved her first podium places in the European Cup in the 2011/2012 season when she was third in the Super-G in Bad Kleinkirchheim and in the giant slalom in Andalo .
In the World Cup , Mugnier started playing for the first time in the 2010/2011 season, initially only in giant slalom and from the 2012/2013 season also in slalom. She won her first World Cup points on December 16, 2012 when she finished 27th in the giant slalom in Courchevel , her ninth World Cup race. After the turn of the year she celebrated her first victories in the European Cup in the two giant slaloms in Zinal . At the Junior World Championships in 2013 she won two bronze medals, in slalom and in combination. Her best World Cup result so far is a 9th place on December 28, 2014 in the giant slalom in Kühtai .