1350, Lachlan Lubanach Maclean of Duart, the 5th Clan Chief, married Mary Macdonald, daughter of John of Islay, Lord of the Isles, and Duart was part of her dowry. John of Islay's son, Donald Macdonald, Lord of the Isles, confirmed the castle by charter to the Macleans in 1390.

In 1647, Duart Castle was attacked and laid siege to by the Argyll government troops of Clan Campbell,