We demonstrate a simple, one-step synthesis of hybrid gold nanoparticle–graphene oxide nanosheets (Au–GO) through electrostatic self-assembly. This method affords a facile means of controlling the effective concentration of the active Au nanoparticles on the graphene sheets, but also offers the necessary stability of the resulting Au–GO nanostructure for catalytic transformation. Furthermore, this hybrid Au–GO is successfully employed in the catalytic reduction of a series of nitroarenes with high catalytic activity. Through careful investigation of the catalyst, we find the synergistic catalytic effect of Au nanoparticles and GO, further highlighting the significance of hybrid Au–GO nanostructure. Considering the wide potential applications of a two-dimensional graphene sheet as a host material for a variety of nanoparticles, the approach developed here may lead to new possibilities for the fabrication of hybrid nanoparticle–graphene nanosheet structures endowed with multiple functionalities.