He lived all his life in Florence, and from his late 30s was kept busy as the court painter of Cosimo I de' Medici, Grand Duke of Tuscany. He was mainly a portraitist but also painted many religious subjects, and a few allegorical subjects, which include what is probably his best known work, "Venus, Cupid, Folly and Time", c. 1544–45, now in London. Many portraits of the Medicis exist in several versions with varying degrees of participation by Bronzino himself, as Cosimo was a pioneer of the copied portrait sent as a diplomatic gift.