King John was no stranger to Knepp Castle, having visited twice in 1206. In 1208, after Matilda de Broase had refused to offer her sons as hostages to John, the King seized all the de Broase property. John made further visits to Knepp and during the barons rebellion, Queen Isabella stayed for eleven days. John eventually restored Knepp to the de Braose family in 1215. With William de Braose, his wife and son now dead, the castle passed to William de Braose' uncle, Giles de Braose, the Bishop of Hereford.
While he held Knepp, John placed the castle under the Stewardship of Roeland Bloet. The forest around Knepp was rich in game and John frequently allowed friends an supporters to hunt in the forest. There remain a number of letters from the King to his steward at Knepp with directions as to the size of the hunting party to accommodate and the type and quantity of game they should be allowed to take. The directions were frequently very precise, detailing the numbers of horses, hounds, keepers and other servants that should be accommodated. The cost of the hunting parties was paid by the exchequer.
John also used the forest around Knepp to supply timber. There are records of timber taken from Knepp being used in construction projects at Dover castle and to build siege towers during the barons rebellion. The timber was transported by sea, most likely loaded at nearby Arundel, which had river access to the sea.