Removing wastewater pollutants using semiconducting-based heterogeneous photocatalysis is an advantageous technique because it provides strong redox power charge carriers under sunlight irradiation. In this study, we synthesized a composite of reduced graphene oxide (rGO) and zinc oxide nanorods (ZnO) called rGO@ZnO. We established the formation of type II heterojunction composites by employing various physicochemical characterization techniques. To evaluate the photocatalytic performance of the synthesized rGO@ZnO composite, we tested it for reducing a common wastewater pollutant, para-nitro phenol (PNP), to para-amino phenol (PAP) under both ultraviolet (UV) and visible light irradiances. The rGOx@ZnO (x = 0.5–7 wt%) samples, comprising various weights of rGO, were investigated as potential photocatalysts for the reduction of PNP to PAP under visible light irradiation. Among the samples, rGO5@ZnO exhibited remarkable photocatalytic activity, achieving a PNP reduction efficiency of approximately 98% within a short duration of four minutes. These results demonstrate an effective strategy and provide fundamental insights into removing high-value-added organic water pollutants.