In the title compound, C(16)H(13)ClN(4)OS, the isatin ring system is oriented at dihedral angles of 10.60 (7) and 72.60 (3)° with respect to the thio-semicarbazide and 2-chloro-benzyl groups, respectively. The near planarity of the isatin and thio-semicarbazide groups [r.m.s. deviations of 0.0420 and 0.0163 Å, respectively] is reinforced by intra-molecular N-H⋯O and N-H⋯N hydrogen bonds, which generate S(6) and S(5) rings, respectively. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R(2) (2)(8) loops. Aromatic π-π stacking inter-actions between the centroids of heterocyclic five-membered and benzene rings [distance = 3.6866 (11) Å] are also observed.