In the title complex, [Cd(C12H11N4S2)I(C12H12N4S2)], the Cd(II) ion is penta-coordinated by two thio-semicarbazone ligands (one neutral and the other anionic) and one iodide ion in a distorted square pyramidal (τ = 0.35) geometry. The central ion is coordinated by the thia-zole N atom, the thio-ureido N and the S atom of the deprotonated thio-semicarbazone ligand. The other ligand is linked with the central ion through the C=S group. The deprotonated ligand intra-molecularly hydrogen bonds to the thia-zole ring N atom, while the ligand forms an inter-molecular hydrogen bond to the thiol-ate S atom of the second ligand. The deprotonation of the tridentate ligand and its coordination to the Cd(II) ion via the S atom strikingly affects the C-S bond lengths. The C-S bond lengths in the neutral and deprotonated ligands in the metal complex are 1.709 (3) and 1.748 (2) Å, respectively, whereas it is 1.671 (3) Å in the free ligand. In the metal complex, the Cd-S distances are 2.6449 (6) and 2.5510 (6) Å. The Cd-I bond length is 2.7860 (2) Å.