The main feature of the castle is the massive gatehouse, which guarded the entrance to a large area enclosed by walls that would have offered good protection to local villagers, their animals and possessions, in the event of a raid from the Scots. In 1362, John of Gaunt, fourth son of Edward III, inherited the castle. He built a new gatehouse about 30m to the left of the original, and had the great gatehouse converted into a keep.

Dunstanburgh Castle was a Lancastrian stronghold during the Wars of the Roses (1455 - 1485), and suffered heavy damage from cannon, leaving the castle in ruins.