In this study, we demonstrated the facile design of zinc-sulphide decorated reduced graphene-oxide (ZnS-rGO) nanohybrid via microwave method and examined their photocatalytic properties. The physico-chemical properties of the ZnS-rGO were analysed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, high resolution scanning electron microscopy, energy dispersive X-ray spectroscopy and laser Raman analyses, respectively. The photocatalytic activity of the prepared ZnS-rGO nanohybrid was examined by the degradation of two model dyes Methylene blue (MB) and Rhodamine-B (RhB). The experimental results suggested that the designed ZnS-rGO nanohybrid possess superior photocatalytic activity with 1.47 and 2.92 fold higher reaction rates for MB and RhB degradation than that of the pure ZnS nanoparticles. A plausible mechanism for the enhanced properties of ZnS-rGO nanohybrid was discussed using photoluminescence spectra. Further, the role of reactive oxygen species on the photocatalytic properties of ZnS-rGO nanohybrid was investigated using appropriate electron and hole scavengers.