Nidau is first mentioned in as Nidowe. The remains of a number of stilt house settlements from the neolithic until the late Bronze Age have been found along the lake shore in Nidau. Along the river, a wooden castle was built in A second castle was built in , which was replaced with the stone Nidau Castle in the early 13th century. The town was built south of the castle.
It was either built or expanded just before the Battle of Laupen in The triangular town pointed toward the castle and had a main street that paralleled the river and ran north—south. Three cross streets ran west from the main street. However, he was defeated in and the Counts of Kyburg acquired the castle. In , Count Rudolf von Kyburg sold the castle and town to the Habsburgs.
The Habsburgs then gave the castle as a fief to Enguerrand de Coucy , the former commander of the Guglers, in During the Sempach War , in May , Swiss Confederation forces from Bern and Solothurn attacked and besieged the town and castle for seven weeks before taking Nidau. The castle was heavily damaged and the Swiss forces suffered heavy losses in the battle. Following the war, the town and castle were awarded to Bern in the peace settlement. In Bern granted the town a charter , though only the version still exists.
The town market and granary were first mentioned in A hospital opened in and a plague house was built in Rich trade allowed the town to grow quickly. Most of the residents worked in the markets, ship building, goods transportation and hospitality. Fishing, viticulture and farming provided most of the food for the town. The local tanners were the only group that formed a guild , beginning in The guild house was built in It became a parish church in when Nidau formed its own parish.
Nidau converted to the new faith of the Protestant Reformation in , along with the Canton of Bern. After the Reformation, the Nidau parish included Bellmund and Port. During the 18th and 19th century, the town was flooded several times when the river or lake rose. The Jura water correction projects of —91, lowered the water level and helped protect the town from floods.
