It is belived that the name Horsens derives from the old Danish words hors (horse) and næs (naze, headland). Since the 12th century the name 'Horsens' has been in use.
Horsens was founded in the 11th or 12th century. It was a fortified town with several monasteries. In the 13th century Horsens got its own legal code. In 1442 the port received its first market charter and had already become a commercial centre by the 18th century. The Franciscan monastery chapel and the late Romanesque Vor Frelsers Kirke (Church of Our Saviour), date from the late 13th century. The city still preserves a museum and several 18th-century merchants’ houses. Since 1853 Horsens also hosts the state prison. Industrialization in Horsens started in the middle of the 19th century. The population increased significantly when people from the countryside moved to the city to work in its factories.