Cirencester Castle was a castle in the town of Cirencester in Gloucestershire, England.

The castle was originally built in the 11th century in timber, with a square keep added in stone in 1107.^[1] The castle was of primarily local significance, being relatively small.^[2] During the Anarchy of the 12th century, the castle was seized in the early years of the conflict by Robert, Earl of Gloucester on behalf of the Empress Matilda.^[3] In 1142 King Stephen seized the castle in a surprise attack, setting fire to it afterwards.^[4]

Subsequent events are disputed by historians. Most 19th-century historians argued that the castle was subsequently rebuilt and held by William de la Dive, a follower of Robert, Earl of Leicester, then a supporter of the Empress.^[4] When Robert came to an agreement with Stephen at the end of the conflict, William surrendered the castle to the king.^[4] During the baronial revolt against Henry III the castle was once again garrisoned against the king; once captured by royal forces, Henry ordered it finally destroyed for good.^[4] Historian E. Fuller argued in 1890, however, that this later history was a consequence of a misreading of place names, arguing that the history of the castle concluded with its destruction in 1142.^[5]