Graphene hybridized with ZnO could produce an efficient photocatalyst. The ZnO nanoparticles were firstly coated with an appropriate amount of graphene oxide, the graphene oxide was then in situ reduced to form the ZnO/graphene composite. Graphene hybridized ZnO photocatalyst showed enhanced photocatalytic activity for the degradation of organic dye. The degree of photocatalytic activity enhancement strongly depended on the coverage of graphene on the surface of ZnO nanoparticles. The sample of 2 wt% graphene hybridized ZnO showed the highest photocatalytic activity, which was about 4 times as that of pristine ZnO. The enhancement of photocatalytic activity was attributed to the high migration efficiency of photo-induced electrons and the inhibited charge carriers recombination due to the electronic interaction between ZnO and graphene. The electronic interaction was systematically studied and confirmed by the photoelectrochemical measurements.Graphical abstractResearch highlights▶ ZnO is surface modified with graphene. ▶ The photocatalytic activity of ZnO is greatly increased by more than 3 times. ▶ The optimum loading amount of graphene is 2.0 wt%. ▶ The electronic interaction retards the recombination of photo-induced charges.