Born at Sèvres, Le Guay was the son of the porcelain painter Étienne Henri Le Guay. He was a pupil of Joseph Marie Vien (1716–1809). He worked as a painter at the Sèvres porcelain factory for a considerable time and exhibited miniatures at the Paris Salon from 1795 until 1819; some of his miniatures were painted on porcelain. His three wives—Marie Sophie Giguet (died 1801), Marie Victoire Jacquotot (1772–1855) from whom he was divorced in 1803, and Caroline de Courtin—were all pupils of his and painted miniatures; Mme Jacquotot and Caroline Le Guay also painted porcelain at Sèvres. Le Guay died in Paris.