In the title compound, C18H20Cl2N2O2S, the piperazine ring adopts a chair conformation. The dihedral angle between the sulfonyl-bound benzene ring and the best-fit plane through the six non-H atoms of the piperazine ring is 72.22 (12)°; those between the dichlorobenzene ring and the sulfonyl and piperazine rings are 2.44 (13) and 74.16 (2)°, respectively. In the crystal, molecules are connected through weak C—H⋯O interactions into a hexameric unit generating a R 6 6(60) motif in the ab plane. The molecules are also connected into C(4) chains through weak C—H⋯N interactions. The solvent used to grow the crystal was a mixture of dichloromethane and methanol, but the resulting electron density was uninterpretable. The solvent contribution to the scattering was removed with the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148–155]. The formula mass and unit-cell characteristics do not take into account the disordered solvent.