d. 3 February 1711
Born in Florence, the son of Grand duke Ferdinando II of Tuscany and Vittoria Della Rovere. In 1683 he was appointed to governor of Siena, a position he maintained until his death. He was the grand prior of the Sovereign Order of Malta in Pisa. Abbot commendatario of S. Galgano, Siena. Abbot commendatario of S. Stefano, Carrara, 1675. According to a family tradition was promoted to the cardinalate at a young age in 1686. He remained in Florence, in his villa of Lappeggi, devoting himself to a life not really religious, made of amusements and love affairs with men. He resigned cardinalate on June 19, 1709 and was named prince of Siena. He then was forced to marry in 1709 Eleonore Luisa Gonzaga, duchess of Guastalla, daughter of Vincenzo Gonzaga, in an attempt to save the dynasty, but they did not have children.