A facile method is proposed for the synthesis of reduced graphene oxide nanosheets (RGONS) and Au nanoparticle–reduced graphene oxide nanosheet (Au–RGONS) hybrid materials, using graphene oxide (GO) as precursor and sodium citrate as reductant and stabilizer. The resulting RGONS and Au–RGONS hybrid materials were characterized by UV–vis spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, atomic force microscopy, transmission electron microscopy, and X-ray diffraction. It was found that the RGONS and Au–RGONS hybrid materials formed stable colloidal dispersions through hydrogen bonds between the residual oxygen-containing functionalities on the surface of RGONS and the hydroxyl/carboxyl groups of sodium citrate. The electrochemical responses of RGONS and Au–RGONS hybrid material-modified glassy carbon electrodes (GCE) to three kinds of biomolecules were investigated, and all of them showed a remarkable increase in electrochemical performance relative to a bare GCE.