Lesage inherited the Maison Lesage, which was bought by his father, Albert Lesage, in 1924. He became well known for his embroidery work throughout the French high fashion houses in Paris. Lesage shepherded the business throughout the late 20th Century, at a time when many other traditional embroidery houses in France disappeared. Under Lesage, the House collaborated with new, well known fashion clients, including Givenchy, Christian Lacroix, Balenciaga and Dior. Lesage partnered with many of the era's best known fashion designers, including Elsa Schiaparelli and Vionnet.
François Lesage sold the Maison Lesage to Chanel in 2002. Chanel had begun its acquisition of many of Paris' top petites mains in a bid to ensure their continued survival in a changing fashion industry.
Lesage was awarded the Maître d'Art from the French Ministry of Culture in November 2011, just one week before his death. At the time, Minister of Culture Frédéric Mitterrand said, "I cannot imagine fashion without embroidery, embroidery without Monsieur Lesage."
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- Frankel, Susannah (2011-12-02). "Farewell to man who gave haute couture its shimmer". The Independent. Retrieved 2011-12-21.
- Wilson, Eric (2011-12-01). "François Lesage, Who Led Embroidery Atelier, Dies at 82". New York Times. Retrieved 2011-12-21.
- "François Lesage obituary". The Telegraph. 2011-12-02. Retrieved 2011-12-21.