Lady Joan FitzAlan was born in 1375, at Arundel Castle, Sussex, England, one of the seven children of Richard Fitzalan, 11th Earl of Arundel, Earl of Surrey, and his first wife Elizabeth de Bohun.
On 21 September 1397, Joan's father, the Earl of Arundel, who was also one of the Lords Appellant, was beheaded on Tower Hill, London, on charges of high treason against King Richard II of England.