La Madelaine-sous-Montreuil (, literally La Madelaine under Montreuil; ) is a commune in the Pas-de-Calais department in the Hauts-de-France region of France.
La Madelaine-sous-Montreuil is situated adjacent to the northwest of Montreuil-sur-Mer on the D139 road and by the banks of the Canche river.