The origins of the community date all the way back to prehistoric times, when the Gallo-Romans called the settlement "Tectis" (from Latin tectum, which means house). During Carolingian times, the Theux district was a popular hunting ground. It had a parsonage and was the King’s property.
In the 11th century, Theux became the seat of the districts of Verviers, Sart, Spa and Jalhay, and in the 16th century became the margraviate of Franchimont. After that, the territory was given to the Bishops of Liège, who ruled it until 1794.
During the industrial age, the community blossomed thanks to the metal industry. Distinct evidence is still visible in many places. Only one month after Paris, the Revolution Franchimontiose of 1789 broke out in Theux-Polleur, bringing the town distinctly more democratic human rights than were enjoyed in France. From the 19th century until 1940, the textile industry also flourished here.