Born Hanne Karin Bayer, she began her career as a model and appeared in several Danish advertising films. She starred in a Danish short that won a Cannes Fiolm Festival Prize, bringing her to Paris; there she met filmmaker Jean-Luc Godard, who launched her film career and to whom she was married from 1961-67. She went on to be a busy screen actress in both French and international films, particularly in the '60s. She wrote, directed, and starred in the film Vivre Ensemble (1973). She is married to director Daniel-Georges Duval.