Mézard joined the Centre national de la recherche scientifique (CNRS) as a researcher in 1981. He was a professor of Physics at the École Polytechnique. In 2001, he joined the Center for Theoretical Physics and Statistical Models at the University of Paris-Sud, and he serves as its director. Since 2012 to 2022, he had also served as the director of his alma mater, the ENS. In 2022 he joined the Department of the Computing Sciences at the Bocconi University in Milan.
