By using a molecular hybridization approach, two series of amido/ureidosubstituted benzenesulfonamides incorporating substituted-isatin moieties were synthesized. The prepared derivatives were in vitro evaluated for their inhibitory activity against human carbonic anhydrase (hCA, EC 4.2.1.1) I, II (cytosolic) and IX, XII (transmembrane, tumor-associated) isoforms. All these isoforms were inhibited in variable degrees by the sulfonamides reported here. hCA I was inhibited with K_Is in the range of 7.9–894 nM, hCA II in the range of 7.5–1645 nM (with one compound having a K_I > 10 μM); hCA IX in the range of 5.0–240 nM, whereas hCA XII in the range of 0.47–2.83 nM. As all these isoforms are involved in various pathologies, in which their inhibition can be exploited therapeutically, the derivatives reported here may represent interesting extensions to the field of CA inhibitors of the sulfonamide type.