The molecule in the structure of the title compound, C15H11ClN2OS, displays two planar residues [r.m.s. deviation = 0.014 Å for the benzimidazole residue, and the ketone group is co-planar with the benzene ring to which it is attached forming a O—C—C—C torsion angle of −173.18 (14) °] linked at the S atom. The overall shape is based on a twisted V, the dihedral angle formed between the two planes being 82.4 (2) °. The amine-H atom is bifurcated, forming N—H⋯O and N—H⋯S hydrogen bonds leading to dimeric aggregates. These are linked into a supramolecular chain along the c axis via C—H⋯π hydrogen bonds. Chains form layers in the ab plane being connected along the c axis via weak π–π interactions [3.9578 (8) Å] formed between centrosymmetrically related chloro-substituted benzene rings.