In 1967, Arthur Butler, 6th Marquess and 24th Earl of Ormonde, sold the abandoned castle to the Castle Restoration Committee of a mere £50, stating: "The people of Kilkenny, as well as myself and my family, feel a great pride in the Castle, and we have not liked to see this deterioration. We determined that it should not be allowed to fall into ruins. There are already too many ruins in Ireland." He bought the land in front of the castle from the trustees "in order that it should never be built on and the castle would be seen in all its dignity and splendour". The castle's hand-over party included many notable people, such as Mick Jagger and Marianne Faithfull. Mick is reported to have told the newspapers, "We just came to loon about.". Also present was Charles Haughey.
The castle was completely restored in the 20th century and opened to visitors. The Butler Gallery, which is housed in the castle basement, holds rotating exhibitions hosted by the Kilkenny Art Gallery Society.