Nidau District is one of the 26 administrative districts in the canton of Bern, Switzerland. Its capital, while having administrative power, was the municipality of Nidau.
From 1 January 2010, the district lost its administrative power while being replaced by the Biel/Bienne (administrative district), whose administrative centre is Biel/Bienne.
Since 2010, it remains therefore a fully recognised district under the law and the Constitution (Art.3 al.2) of the Canton of Berne.
Although the district is officially German speaking, a small French-speaking minority lives in the area. The district has an area of 113 km<sup>2</sup> and consisted of 25 municipalities: