A novel g-C3N4/Fe-ZnO/RGO nanocomposite has been synthesized using the facile solvothermal method to boost the catalytic efficiency of ZnO. The structure and morphology of nanocomposites were examined by a wide range of characterization methods. The obtained g-C3N4/Fe-ZnO/RGO nanocomposite (Z-scheme heterostructure) exhibits improved photocatalytic activity toward the photodegradation of MB, Cr (VI) under visible-light irradiation and 4-nitrophenol reduction. The enhancement in activity of nanocomposite is ascribed to a unique heterostructure system, which facilitates excellent transport and separation of the photogenerated charge carrier, resulting in prolonged lifetime leading to continuous generation of reactive species. Moreover, the synergistic effect on the interface of ZnO and g-C3N4 and the introduction of reduced graphene oxide (RGO) serve as a booster for charge separation at the Z-scheme, which ultimately speeds up the degradation of pollutants. The present study provides a novel and facile approach for establishing an efficient nanocomposite for environmental remediation.