The British company "Dennis" was founded in 1895, when engineer John Dennis, together with his younger brother Raymond, assembled his first bicycle, and just a few months later he opened a small company to manufacture them. However, since 1897, the brothers began experiments on installing an internal combustion engine on a bicycle. So, several prototypes of mopeds were presented, and in 1900, cooperation with the French company "De Dion-Bouton" began.

In the same year, the first passenger car of a small company was presented, which received a single-cylinder 2 horsepower engine. By 1904, more than 500 copies of the Dennis Brothers were sold. However, in the same year, the brothers developed a light cargo van, which left far behind all the company's previous products in terms of sales. Under the hood of the 15cwt was a 12 horsepower White & Pope power unit. In 1905, the first Dennis bus was presented, and a year later the legendary double-decker buses, which are one of the symbols of Great Britain and London, went on sale. Two years later, on a wave of success, Dennis began producing fire engines and two-ton trucks equipped with a three-speed gearbox and engines with a capacity of 24 and 35 horsepower, respectively. By the beginning of World War II, Dennis had become one of the largest car companies in Great Britain, but by the beginning of 1940 all of its factories were completely destroyed by German aircraft. Production was resumed only in 1945.

By 2000, Dennis had become one of the largest and most popular manufacturers of buses and trucks in the UK, with a full focus on industrial and commercial models since the late 1980s. The company no longer manufactures passenger cars.