Graphene (G) based nanomaterials received a lot of attention in the field of photocatalytic waste water treatment. It has been extensively explored and utilized for the alteration of semiconductor photocatalysts due to its exceptional properties i.e. high specific surface area, high electron conductivity and high thermal stability. On the other hand, zinc oxide (ZnO) as a photocatalyst possesses excellent qualities as strong oxidation ability, good photocatalytic property, chemical stability, biocompatibility, non-toxicity, high photosensitivity, piezoelectric and pyroelectric properties. But inherited with some limitations such as absorption in Ultraviolet (UV) region, photocorrosion etc. as a consequence of modification due to demand of visible light active photocatalysis. Hybrid of ZnO with graphene based nanocomposites is an alternative for the degradation of organic and inorganic contaminants present in water. This chapter presents an overview of the numerous methods used for synthesis and applications of graphene based nanomaterials (graphene oxide (GO), reduced graphene oxide (rGO)), ZnO and their coupling with highly porous ZnO nanoparticles (NPs). Accordingly, graphene supported ZnO nanocomposites are better electron collectors that strongly obstruct electron-hole pair recombination and enhance the visible light adsorption for productive usage of solar energy. Keywords: ZnO, Graphene, Photocatalysis, Supported photocatalytic system, Wastewater treatment