In the title compound, C(20)H(17)ClO(3), the naphthalene and benzene rings form an inter-planar angle of 83.30 (8)°. The conformation around the central C=O group is such that the C=O bond vector forms a larger angle to the plane of the naphthalene ring than to the plane of the benzene ring, viz. 55.8 (2)° versus 15.8 (2)°. The 4-chloro-phenyl groups form a centrosymmetric π-π inter-action, with a centroid-centroid distance of 3.829 (1) Å and a lateral offset of 1.758 Å. An inter-molecular C-H⋯O inter-action is formed between the 4-chloro-phenyl group and the O atom of a neighbouring meth-oxy group, and two very weak C-H⋯π contacts are present.