Pickering Castle is a motte-and-bailey fortification. The original structure was built by the Normans under William the Conqueror in 1069. This early building included the large, central mound (the motte), the outer palisades (enclosing the bailey) and internal buildings, notably the keep on top of the motte. Ditches were also dug to make assault on the walls difficult. The main purpose of the castle at this time was to maintain control of the area after the harrying of the North. Pickering Castle is set in an attractive moors-edge position. Pickering Castle is a good example of a Norman motte-and-bailey castle where the original wooden defences were gradually replaced by stone. The castle proved popular with many later kings who used it as a base for hunting in the surrounding forest.

The castle consists of a large motte surrounded by its own ditch and around this are two baileys. King Henry II began the process of rebuilding the castle in stone, when construction of a new curtain wall around the inner bailey was started in 1180. Over the next sixty years the defences of the inner bailey were further developed, including the building of a circular shell keep on top of the motte. By contrast the outer defences remained in timber until the early 14th century, when King Edward II ordered repairs and improvements to the castle that included the construction of a stone curtain wall around the outer bailey. Surveys in the 1530's describe a castle already falling into decay, and by 1651 the chapel was the only building still roofed and usable. The chapel is still the only surviving roofed building, although it was greatly restored in the early 19th century and re-roofed more recently. In 1926, the Department of Works took possession of the castle.