He was 65 years old when he came to office (born November 16, 1436) and had made his fortune in trading.
He served the Republic in numerous posts and was finally elected prosecutor of S. Marco de citra on the 2nd of July 1492. His dogeship was one of the most important for the great events it brought, managing to protect Venice in a very difficult period of its history. He had to accept an onerous peace with the Turkish empire (1503), but succeeded in expanding the Venetian dominion of land to Trentino, Friuli, Istria and Illyria. However, the largest expansion ever achieved by the Republic attracted political jealousies and the Doge had to face the League of Cambrai which began a long war (1509 -1517) in the Venetian territories of the mainland.
Upon his death, Leonardo Loredan was buried in the Church of S. Giovanni e Paolo. The funeral monument, dated 1572, was the work of Girolamo Grapiglia. The portrait of the Doge by Giovanni Bellini is interesting: it is one of the first frontal portraits of a reigning Doge; men were usually portrayed in profile during the Middle Ages, while the front view was reserved for sacred subjects. He is commemorated in the Panteon Veneto with a bust by the sculptor Luigi Borro, kept in the Palazzo Ducale.
Under his dogeship the first Jewish Ghetto was founded on the 29th of March 1516 by decree of the Venetian Senate.