A one-pot and efficient catalytic protocol has been developed to synthesize pharmaceutically critical 2-substituted benzimidazoles and benzothiazoles using magnetite dopamine-supported copper nanoparticles (Fe3O4@PDA/CuCl2) as a heterogeneous catalyst. This selective transformation proceeds via oxidative cross-coupling of readily available benzylic amines with o-phenylenediamine/2-aminothiophenol. This one-pot green method proceeds smoothly, under mild conditions, avoids the usage of toxic metals, tolerates a variety of functionalities, and is amenable to gram scale. Furthermore, this easy-to-prepare magnetic nanocatalyst can be separated by magnetic decantation after the reaction, thereby making it more sustainable.