Primarily a power skiier, Isabelle Mir won a silver medal in the downhill at the 1968 Winter Olympics and at the 1970 World Championships. In addition, she was World Cup downhill champion in both 1968 and 1970, winning eight downhill World Cup races and one giant slalom. She won her first World Cup race in March 1967 at Franconia, New Hampshire, and her final one, her only giant slalom victory, in February 1971 at Mont Ste-Anne, Canada. In the 1967-68 season she was runner-up in the overall World Cup and in all, she had 24 podium finishes on the World Cup circuit. Mir was also French champion in the downhill from 1968-70.
After her retirement from skiing, Mir developed sports shops and mountain restaurants, the first one in Avoriaz, along with Annie Famose. She and Famose also developed new training techniques for children. Isabelle Mir’s cousin, Jean-Pierre Mir, was a rugby player for FC Lourdes, playing a single international in 1967.