The area around Sornetan was inhabited since antiquity. Some of the earliest finds are scattered items from the Celtic tribes that lived in the area. They were followed by the Romans and then by the Burgundians. A noble family using the Sornetan name appear in historic records from the 12th until the 14th centuries. The village was eventually acquired by the college of canons of Moutier-Grandval Abbey. When the Abbey was suppressed during the Protestant Reformation, Sornetan was placed under the provost of Moutier-Grandval who was under the Prince-Bishop of Basel. After the 1797 French victory and the Treaty of Campo Formio, Sornetan became part of the French Département of Mont-Terrible. Three years later, in 1800 it became part of the Département of Haut-Rhin. After Napoleon's defeat and the Congress of Vienna, Sornetan was assigned to the Canton of Bern in 1815.