The Gallic settlement on a rocky peak over the Rhône was called Bergoiata. Near the town is a sculpted bas relief of the god Mithras. It acquired its present name after Saint Andeolus, the 'apostle of the Vivarais', a disciple of St. Polycarp, supposedly arriving from Asia Minor, who evangelized the area under Emperor Septimius Severus, and was martyred in 208. The region was named Helvia in Julius Caesar's De Bello Gallico, with Alba-la-Romaine as capital city, then Vivarais from the mediaeval times after the see of Viviers, a region of Languedoc province during Ancien Régime until départements were created at the French Revolution. Due to the citizen's engagement for the Revolution, the town's name rejected a while the little known saint and was named Bourg-sur-Rhône. (At the Napoleonic times, Andéol had already been brought in back...)
It had been the seat of a bailli (royal magistrate). And the bishop of Viviers had settled several decades in Renaissance times in the city (the Bishops' Palace). It is the seat of the mother houses of the Congregation of the Presentation of Mary and of the Religious Congregations of the Presentation.
The city had grown and become one of the most important towns of county Vivarais due to its position on the Rhône (boatmen mariniers du Rhône, trade and business in hide, fabric, wine, oil). Several patricians' houses are still to be seen in the centre of the city (although a part of it was bombed by Allied forces at the end of World War II, missing the hanging bridge - which was replaced afterwards by the existing one).