Anthonioz made her World Cup debut in 1996 at the races in Tignes , where she started in the giant slalom and finished sixteenth. Also in 1996 she was junior world champion in this discipline, this success repeated in 1997. In January 1998 she played her last giant slalom. Then she paused until the 2001/2002 season . Since then she has only started in snowboard cross at the World Cup. Her first victory came in January 2002 when she won the competition in Kreischberg . Further victories followed in 2003 in Bad Gastein , 2004 in Nassfeld-Hermagor and 2005 in the Chilean Valle Nevado . In the 2004/2005 season she had her most successful time to date and finished second in the snowboard cross discipline in the World Cup.
Her best placement at world championships she also achieved in 2005 when she was sixth. In 2003 she reached eighth place and in 2007 she cut eleventh. Also in 2009 in Gangwon , she was twelfth outside the medal ranks. She had already qualified for the Olympic Games in 1998, but suffered an ankle injury and had to do without a start. She started in her specialty discipline at the 2006 Olympic Games in Turin and was tenth despite a broken right arm in a cast . Anthonioz was more successful at the 2010 Olympics in Vancouver, behind Maëlle Ricker she won the silver medal and relegated Olivia Nobs to third place. Before the Olympic Games, she had not been able to achieve a top ten result in the 2009/2010 season , after which she convinced at the end of the season with a sixth and a seventh place in Valmalenco and La Molina . In April 2010 she was again French champion in snowboard cross after 2005 and 2007.