The town, now in northwest Switzerland, lies at the foot of the Jura Mountains and to the northeast of Lake Biel (Bielersee).
It was founded by the Bishop of Basle, and remained part of the Prince-Bishopric at least in name until the revolutionary era, but in 1529 Biel and the district around it became allied to Bern and thence to the Swiss Confederates. By 1579 most of the Bishop’s lands south of the Jura had joined the alliance. Protestantism became the religion of the district.
In 1798 the district was annexed to France and was added to the Department of Mont-Terrible (the former Bishopric of Basle), which was abolished in 1800, when its lands were added to the Haut-Rhin. In 1815 most of the former Bishopric, including Biel, was transferred to the Canton of Bern.
The border between the French- and German-speaking parts of Switzerland runs through the town. Two-thirds of its people speak German and one-third French, so it is officially bi-lingual, and is generally known as BIEL/BIENNE.