Born in Dieppe, Seine-Maritime as the daughter of farmers, she grew up in Gonzeville and then studied at the Rouen Conservatoire - a dance, music and drama school. Lemercier made her screen debut in 1988, in the television series Palace. Lemercier has won two César Awards for her supporting roles in Les Visiteurs (1993) and Fauteuils d'orchestre (2007), and hosted the award ceremony in 2006 and 2007. She has subsequently become a successful director.
She released her first music album, Valérie Lemercier chante, in 1996, and has subsequently recorded three singles with other singers.