Noyon was strongly fortified in Late Antiquity. It is a possible explanation that around 531, bishop Medardus moved his see from Vermand, in the Vermandois, to Noyon. Other explanations are that Medardus was borned near the town, at Salency, or that place is nearer from Soissons, which was one of the royal capitals of Merovingian dynasty.
The cathedral at Noyon was the site where Emperor Charlemagne was crowned in 768 as was the first Capetian king, Hugh Capet in 987. The town received a communal charter in 1108, that was confirmed by Philip Augustus in 1223. In the twelfth century, the bishop of Noyon was raised to an original duché-pairie in the peerage of France. The Romanesque cathedral burned in 1131. The present cathedral, a monument of the Early Gothic style in France, was erected between 1145 and 1235. The bishop's library is a historic example of half-timbered construction.
By the Treaty of Noyon, signed 13 August 1516 between Francois I of France and Charles V, Holy Roman Emperor, France abandoned its claims to the Kingdom of Naples and received the Duchy of Milan in recompense; the treaty brought the War of the League of Cambrai— one stage of the Italian Wars— to a close. Having been ravaged by Habsburg troops in 1552, Noyons was sold to France in 1559, under the conditions of the Treaty of Cateau-Cambrésis. Near the end of the sixteenth century the city fell under Habsburg control, but Henry IV of France recaptured it. The Concordat of 1801 suppressed its bishopric. The city was occupied by the Germans during World War I and World War II and on both occasions suffered heavy damage.