The Donjon de Niort or Château de Niort is a medieval castle in the French town of Niort in the département of Deux-Sèvres. It consists of two square towers, linked by a 15th-century building and dominates the Sèvre Niortaise valley.

The castle houses the following museum collections:- archaeological museum on the ground floor with Bronze Age, Gallo-Roman and Middle Ages exhibits- museum of chamois leather and glove making on the first floor- a reconstructed Poitevin interior from 1830 is found on the second floor, as well as a nationally important collection of costumes, headgear and jewelry. From the roof, there is a beautiful view over the town and the Sèvre Niortaise.