Biddlesden is a village and civil parish in Aylesbury Vale district in north-west Buckinghamshire, England on the boundary with Northamptonshire. It is about east-north-east of Brackley, Northamptonshire and north-west of Buckingham. The River Great Ouse forms part of the western boundary of the parish, separating the village from Northamptonshire. The ancient royal forest of Whittlewood extended to the northern edge of the village.