This castle was originally a fortified house, built by the Cossonay-Prangins in the middle of the XIIth century. The counts of Savoir took it in 1293 and transformed it significantly from 1360 (adding the two towers on the lake side of the castle, and probably an inner courtyard. In 1536, during the reformation, the Maison de Savoie, driven out by the Bernese, left Nyon.

Large constructions were done by Their Excellencies from Bern from 1574 to 1583, and gave the actual shape of the castle. After the revolution of the Canton of Vaud in 1798, the castle was bought in 1804 by the city of Nyon and the new born Canton de Vaud. The building hosted the Court, the general assembly, prisons and, since 1888, the museum.

Loosing small by small its defensive characteristics, the castle has become mainly an administrative building. In 1947, the houses situated in front of the castle were destroyed and allowed the arragement of a vast place; the vision on the fortress has been completely changed.

Four centuries after the bernese constructions, the castle was fully restaured between 1999 and 2006.