The copper-catalyzed cascade cyclization of 2-haloaryl isoselenocyanates with isocyanides to access benzo[d]imidazo[5,1-b][1,3]selenazoles has been realized efficiently under ligand-free conditions. The less commonly developed isoselenocyanates served as the selenium sources for the preparation of a new class of selenium-containing heterocyclic compounds. This protocol was designed to involve sequential intermolecular [3 + 2] cycloaddition and intramolecular Ullmann-type C–Se bond formation.