Giant Schnauzers, known as Riesenschnauzers in Germany, were originally bred for cattle herding by farmers in the Bavarian and W├╝rttemberg regions of Southern Germany during the later part of the 19th Century. The farmers who wanted a larger version of the Standard Schnauzer, produced the Giant Schnauzer by selectively crossing the Standard Schnauzer with the Great Dane, Bouvier des Flanders and Rough Haired Sheepdogs. Both Giant and Miniature Schnauzers were bred from the older Standard Schnauzer.

Giant Schnauzers were a popular herding breed, but their need for more food than other breeds made them less popular where farmers were on tight budgets, with limited resources. There were also employed as a guard dogs in breweries and stockyards, police dogs, and during World War I as military dogs. They became scarce during World War II, but their popularity grew again after the war, when they were used as drovers, police dogs and guard dogs.

Although gaining popularity, even today, the Giant Schnauzer remains a rare breed throughout the world.