ruler of Florence from 1513 to 1519, to whom Niccolò Machiavelli addressed his treatise The Prince, counselling him to accomplish the unity of Italy by arming the whole nation and expelling its foreign invaders.

Lorenzo's father, Piero, son of Lorenzo the Magnificent, was driven out of Florence by the republicans, who were aided by the French, when Lorenzo was but two years of age. The papal-led Holy League, aided by the Spanish, however, finally defeated the rebels in 1512, and the Medici and Lorenzo the Magnificent's constitution were restored to Florence.

Lorenzo's uncle Cardinal Giuliano ruled in Florence for one year but then, in August 1513, turned the lordship over to Lorenzo. Lorenzo, being of more ambitious temper, was by no means content to remain at the head of the Florence government hampered by many restrictions imposed by republican institutions and subject to the incessant control of the pope. In his eagerness to aggrandize his kinsmen, the Pope nevertheless decided to give Lorenzo the Duchy of Urbino and formally invested him in its rights, after expelling on false pretenses its legitimate lord, Francesco Maria della Rovere. Francesco Maria, however, soon returned to Urbino, where he was welcomed by his subjects, and Lorenzo regained possession only by a protracted war, in which he was wounded. In 1519 he died, worn out by disease and excess. By his marriage with Madeleine de la Tour d'Auvergne, he had one daughter, Caterina de' Medici (known in France as Catherine de Médicis), who was married in 1533 to Henry, duke d'Orléans, afterward king of France, as Henry II.