Sully-sur-Loire (French pronunciation: [syli syʁ lwaʁ], literally Sully on Loire) is a commune in the Loiret department, north-central France.

The château of Sully-sur-Loire dates from the end of the 14th century and is a prime example of a medieval fortress.

The château was expanded by Maximilien de Béthune, first duke of Sully and prime minister of King Henry IV of France (1560–1641), who is buried on the grounds of his château.

The family of the dukes of Sully retained ownership of the château until the 20th century.

King Louis XIV, his mother Queen Anne of Austria and prime minister Cardinal Mazarin sought refuge in the château of Sully-sur-Loire in March 1652 after they were driven out of Paris during the revolt of the French nobility known as the Fronde.