The title compound, C40H22Cl2O4, was formed by a Michael–Aldol domino reaction sequence, which coupled acenaphthenequinone with 4-chloroacetophenone in the presence of KOH in methanol. The dihedral angles between the central cyclopenta[a]acenaphthylene fused-ring system (r.m.s. deviation = 0.066 Å) and the 4-chlorobenzoyl rings are 62.25 (10) and 70.19 (10)°. The dihedral angle between the central ring system and the naphthoic acid grouping is 62.46 (7)°. This twisting of the pendant rings facilitates the formation of an intramolecular aromatic π–π stacking interaction between the 4-chlorobenzoyl and naphthoic acid rings, with centroid–centroid distances of 3.4533 (16) and 3.5311 (16) Å, and a C—H...π interaction between one of the H atoms of the central moiety and the 4-chlorobenzoyl ring with an H...π distance of 2.57 Å. In the crystal, carboxylic acid inversion dimers generate R22(8) loops. The dimers are linked by weak C—H...O and C—H...Cl hydrogen bonds and C—H...π interactions, generating a three-dimensional architecture.