In this research, the synthesis of high-quality zinc oxide (ZnO) and graphene oxide (GO) nanocomposite (ZnO/GO nanocomposite) was carried out using the simple and efficient hydrothermal method. The ZnO and GO were separately synthesised by using the precipitation and modified Hummer’s method, respectively. Likewise, the effects of different concentrations of GO on the structural and optical properties of ZnO nanoparticles were investigated. All the desired samples were structurally characterized by X-ray diffraction (XRD) and Raman spectroscopy. Those structural characterised techniques indicate the presence of characteristic peaks of ZnO, GO and related elements in the ZnO/GO nanocomposite. Scanning electron microscopy showed that some portions of the spherical shaped ZnO nanoparticles reacted with GO nanosheets to form ZnO nanorods with the formation of reduced graphene oxide (r-GO). UV-Visible and photoluminescence spectroscopy revealed that the optical properties of the ZnO/GO nanocomposite were affected by the GO concentration. The narrowing of optical band gap in the ZnO/GO nanocomposite was observed to pure ZnO sample. The improved optical properties displayed by the ZnO/GO nanocomposites makes them suitable for applications like UV-Vis optoelectronics devices and photocatalytic applications.