The Ardennais is of ancient origin, named after the mountainous Ardennes region of France, on the Belgian border, where the severe climate produces extremely hardy horses. It is a stocky compact draught horse, powerful and large boned, but with an exceptionally docile nature. The head is of medium size with a straight profile and open nostrils, slightly prominent eye sockets with large kind eyes, a low flat forehead and well-shaped ears. The neck is of medium length, well set on and generally arched. The shoulders are powerful and the chest is deep; the back is short with well-muscled loins and the body is generally heavy; the quarters are round and wide; the limbs are short and strong. It stands between 15.h.h. and 16.h.h. and it is ideally suited for all types of draught work. It is more usually roan, red roan, iron grey, dark or liver chestnut or bay in colour, though bay-brown, light chestnut and palomino are admissible. Black, dappled grey and all other colours are inadmissible.

The earlier Ardennais horses used to be smaller in stature and were used not only for draught work but also for riding. In 1810 Arab blood was introduced and later Thoroughbred, Percheron and Boulonnais. These attempts to improve the breed were not very successful and were abandoned. The breed went on to be a great help to the military as an artillery horse both during the Revolution and the Russian campaign and later in World War 1. The development of the heavier stamp of Ardennais was largely due to the requirements of agriculture, though the smaller type is still in existence today. Two other larger versions of the breed are now recognised; The Auxios and the even heavier Ardennais du Nord, a cross with the Belgium Draught.