Bicyclic isothiazole ring systems are privileged structural motifs found in many pharmaceutical compounds and functional materials. They have been widely used as significant privileged scaffolds in a myriad of areas such as organic electroluminescent materials, semiconductors, pesticides, anticancer drugs, and ligands. Thus, development of an efficient synthetic method for functionalized bicyclic isothiazoles is highly desired. Therefore we developed an intramolecular Rh(I)-catalyzed transannulation of readily available cyanothiadiazoles containing an ester, amide, or ether as a linker, serving as an efficient platform for the construction of a wide range of bi-, tri-, and tetracyclic isothiazoles in good to excellent yields together with the release of molecular nitrogen. These results suggest that the carbon atom in the α-thiavinyl carbene is nucleophilic and that the sulfur atom is electrophilic.