Manganese dioxide nanostructures were coated on natural silk (MnO2@silk) by simple immersion of the silk fibers into a KMnO4 aqueous solution. The silk was found to act as a in situ reducing agent and substrate in aqueous KMnO4 solution for the heterogeneous production of MnO2 nanostructures. The structure of synthesized catalyst was characterized by X-ray diffraction (XRD), flame atomic absorption spectroscopy (FAAS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The catalytic activity of the MnO2@silk was examined in the aerobic oxidation of alkyl arenes, alcohols, and oximes to their corresponding carbonyl compounds and a one-pot tandem oxidative two-component reaction of aromatic hydrocarbons of petroleum naphtha in the absence of any other oxidizing reagent or initiator.