uérard served his apprenticeship at the patisserie of Kleber Alix, in Mantes-La-Jolie. He worked at a number of Parisian restaurants, including Maxim's, and in 1958 won the Meilleur Ouvrier de France Patisserie, while working as a pastry chef at the Hôtel de Crillon. He also worked at Le Lido.
In 1965 Guérard opened a restaurant in Paris called Le Pot-au-Feu, which in 1967 earned Guérard his first star in the Michelin Guide. The restaurant gained a second star in 1971, and was successful until it was compulsorily acquired for the purposes of a road-widening.
In 1972 Guérard met Christine Barthelemy, the daughter of the founder of the Biotherm range and the owner of a chain of spas and hotels. They married, and in 1974 he moved with her to Eugénie-les-Bains, where she was running one of her family's smaller, less successful spas. They restored the buildings, and Guérard invented a style of food, cuisine minceur, a form of healthy cooking, designed to lure health-conscious Parisians to travel the 800 km to Eugénie. In 1977 his main restaurant received three Michelin stars, and all his properties in Eugénie have been very successful, transforming the tiny village into a significant tourist destination.