Born in Paris, son of a coachman in the Royal Household, he was taught briefly by his step-father, Robert Tournières, then by Louis Galloche. In 1711 he won the Grand Prix at the Académie, without going to Rome.
In 1716 he was agréé (candidate) by the Academy, in 1718 reçu as a full member. The next twenty years of his career he received numerous prestigious commissions by religious patrons, collectors and by the Royal administration. He produced nine paintings for the monastery of the Cordeliers in Amiens 1717-1720 (five now in Sens Cathedral) and became a leadeing painter of religious subjects. In 1721 he met the financier François Berger (see P392, P417), who became his influential patron and with whom he visited Bologna, Rome, Naples and Venice in 1723-1724. Berger regularly commissioned works from Lemoyne. In 1727, the painter took part in the competition for history painters, organised by the Duc d'Antin, Directeur des Bâtiments du Roi. Lemoyne (with the "Continence of Scipio", Nancy, Musée des Beaux-Arts) and Jean-François de Troy shared the first price and as a consequence became the two dominating figures in French history painting of the 1730s.
In 1733-1736 painted the great ceiling at Versailles of the "Apotheosis of Hercules" in the Salon d'Hercule in Versailles as his crwoning achievement, a work that was universally admired. He was immediately made Premier peintre du Roi (First Painter for the King). But he was already suffering from depression and paranoia, and acute paranoia led to his suicide in Paris on 4 June 1737 (see P392).
Lemoyne was the leading history painter of his generation. His enormous influence on the later courese of French painting was based on the extraordinary quality of his works and on his teaching. Boucher and Natoire were his pupils in the 1720s, as was Donat Nonotte, his biographer, 1731-1737; he also taught drawing to the engraver Laurent Cars. His work transformed the style of Watteau's generation into a grand but very sensuous history painting, mainly inspired by Venetian painters.