Denis Gasquet is an alumnus of the Ecole Polytechnique, a graduate of the ENGREF and holds an MBA from the Centre de Perfectionnement des Affaires. In 1979, he began his career in the ONF. Ten years later, he joined the Compagnie Générale des Eaux. He then served in various positions of responsibility within Onyx and Veolia Environnement. He joined the Onet Group in 2012 and was its General Manager from August 2013 to September 2018. Since 2019, Denis Gasquet has worked as an independent consultant.