The 3D hierarchical ZnO/Bi2MoO6 heterojunctions were fabricated via an in-situ solvothermal method. To the best of our knowledge, this is the first report based on synthesis of ZnO/Bi2MoO6 heterojunction by decoration of ZnO nanoparticles on the surface of the flower-like Bi2MoO6 superstructures. The prepared ZnO/Bi2MoO6 heterojunctions exhibited the characteristic diffraction peaks of ZnO and Bi2MoO6 with the band gap energy of 3.25 eV and 2.76 eV, respectively. The PL intensity of the 10 wt% ZnO/Bi2MoO6 heterojunction (denoted as 0.10Zn-Bi) is much lower than that of the bare Bi2MoO6, indicating much more effective separation of photo-generated electrons and holes at the interface which in turn results in greater expected photocatalytic performance. The 0.10Zn-Bi heterojunction showed the highest efficiency of 100% and 92% toward photodegradation of OFL antibiotic and RhB dye, respectively, due to the greatest surface area and the lowest electron-hole recombination rate. The photodegradation of the pollutants followed pseudo-first order kinetics with a very high rate constant of 0.0196 min(-1). The chemical structure of photocatalyst remained stable after five cycles of use. The photogenerated electron (e(-)) and hole (h(+)) are two major reactive species involved in photodegradation of both OFL antibiotic and RhB dye. The present work demonstrates a very high potential of the 3D hierarchical ZnO/Bi2MoO6 heterojunctions for environmental remediation. (C) 2020 Elsevier Inc. All rights reserved.