Souldern is a village and civil parish in Oxfordshire about 7 miles northwest of Bicester and a similar distance southeast of Banbury. The parish is bounded to the west by the River Cherwell and to the east by field boundaries. Its northern boundary is Ockley Brook, a tributary of the Cherwell that forms the county boundary with Northamptonshire. The parish's southern boundaries are the main road between Bicester and Adderbury and the minor road between Souldern and Somerton.