In this work, ZnO nanoparticles-reduced graphene oxide (rGO) composites were fabricated via a novel one-step photochemical method. The developed nanocomposite offered high photodegradation efficiency of methylene blue (MB) under UV and visible light. In the proposed route, the reduction of graphene oxide (GO) and formation of ZnO nanoparticles occurred simultaneously, which results in high synthesis efficiency of ZnO/rGO nanocomposites. The electron microscopy confirmed that the ZnO nanoparticles were uniformly anchored on rGO sheets. The structure and quality of prepared nanocomposite were assessed by X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Furthermore, the synthesis of the nanocomposite and degradation of MB, along with a mechanistic insight, is discussed in detail. (C) 2018 Published by Elsevier Inc.