Lorenzo di Piero de' Medici (September 12, 1492 – May 4, 1519) was the ruler of Florence from 1513 to his death from the plague 1519. He was also Duke of Urbino from 1516 to 1519.

Born in Florence, he was a son of Piero di Lorenzo de' Medici and Alfonsina Orsini. His paternal grandparents were Lorenzo the Magnificent and Clarice Orsini. His maternal grandparents were Roberto Orsini, Conte Tagliacozzo and Catherine San Severino. Niccolò Machiavelli dedicated The Prince to Lorenzo to inform him of tactics to use in unifying Italy, though the entire intent behind this dedication is shrouded in mystery.

His uncle, the Medici, Pope Leo X, made "Lorenzino" duke of Urbino in 1516 at the age of 24. After the short reconquest by the former duke, Francesco Maria I della Rovere, Lorenzo was named commander of the 10,000 men sent to recapture it, but was wounded and retired to Tuscany. Lorenzo regained the duchy by a treaty short in the September of the same year (War of Urbino). The territory reverted to the Della Rovere family after Lorenzo's death.

As Duke of Urbino, he married Madeleine de la Tour, daughter of the Count of Auvergne, on June 13, 1518; the marriage produced a daughter, Caterina, who was born 21 days before his death. She went on to become Catherine de' Medici, the famous queen of Henry II of France, in a marriage arranged by her uncle, the Medici pope Pope Clement VII, in his last successful move.

His tomb in the Medici Chapel in the Church of San Lorenzo is ornamented with the Twilight and Dawn of Michelangelo, along with Michelangelo's statue, the Pensieroso, of Lorenzo. Due to the identical name he shares with his grandfather (they are both Lorenzo di Piero de' Medici), whose tomb is also in the Medici chapel, this tomb is often mistaken for that of his grandfather.