Nidau is a municipality in the Biel/Bienne administrative district in the Canton of Bern in Switzerland.

Nidau is first mentioned in 1196 as Nidowe. In 1352, it was recorded in Latin as Nydow.

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. A La Tene artifact was discovered in the Thielle/Zihl canal. Several iron ingots which were probably from the Roman era were found in the old Thielle/Zihl river.