East Cowes Castle was an artillery fort built in 1539-42 by Henry VIII as part of his network of coastal fortifications to defend against the threat of French and Spanish invasion. In conjunction with West Cowes Castle, located on the other side of estuary mouth, it defended the entrance to the River Medina and Cowes Harbour. The fortification was abandoned around 1546-7 and was in ruins by the 17th century. No remains of the castle have survived; however the place where the castle stood still retains the name of Old Castle Point.
No details of the castle are known although from the size of its garrison and the amount spent on its construction it may have been similar to that of West Cowes Castle. Stone from the dissolved abbeys at Beaulieu and Quarr may have been used for its construction.