Borstel is a municipality in the district of Diepholz, in the state of Lower Saxony, Germany. It is located in the northwestern part of the country, within a district whose administrative seat is the town of Diepholz.
As a municipality, Borstel forms part of the local administrative structure of Lower Saxony, one of Germany's sixteen federal states. The district of Diepholz lies in the western portion of the state, between the cities of Bremen to the north and Osnabrück to the southwest.