This breed was established in 1846 in Leonberg, Germany in the region of Wurttemberg by the German breeder Heinrich Essing from a crossing of the Newfoundland, St. Bernard, and the Great Pyrenees. Heinrich Essing was attempting to create a breed that would closely resemble the lion in the local town crest. The Leonberger's tawny coloration and thick mane are evidence of his success.

Many royal families have owned Leonbergers, including Empress Elizabeth of Austria, Napoleon II of France, the Prince of Wales, Emperor Napoleon II, Bismarck, and Italian King Umberto. Many Leonbergers were imported to Russia in the nineteenth century. However the two world wars almost destroyed the breed. It was very difficult to feed the huge breed when food was scarce. By the end of World War II, only a few dogs remained.

In 1945, several Germans gathered some of the few remaining Leonbergers and re-established the breed. Today the Leonberger has regained his popularity in Europe. The first Leonberger was imported to the United States in 1971, and there are currently close to one thousand registered today. This versatile breed has been successful in many endeavors. The Leonberger has been used for guarding livestock, obedience and tracking. The breed is also used in Germany for search and rescue and has a reputation as a great water-rescue dog. The Leonberger's warm, gentle personality makes him a fine family companion dog. The official standard was set in 1949.