The Priory Church dedicated to St Mary and to St Blaise dates from the early 12th century. Located close to the South Downs, it stands on the site of an earlier Anglo-Saxon parish church that predates the Norman Conquest. It adjoins the remains of a Benedictine Priory which fell into ruin following the Dissolution of the Monasteries in 1536.

Although it has lost its original nave, the interior of the Priory retains examples of Norman and Early English Gothic architecture. The Chantry Chapel was added in the 16th century by Thomas West, 9th Lord de la Warr, Lord of the Manor of Halnaker and patron of the priory. He also had the ceiling of the nave painted with the arms and badges of his and his wife's families, entwined with flowers and foliage.