A nanocomposite of Au nanoparticles (AuNPs), reduced graphene oxide (RGO) and tungsten oxide (WO3) (AuNPs/RGO/WO3) was fabricated by the one-pot polyol method followed by metal organic decomposition (MOD) method. The novel AuNPs/RGO/WO3 nanocomposite was used to modify a glass carbon electrode (GCE) for the sensitive and simultaneous sensing of hydroquinone (HQ) and catechol (CC). The AuNPs/RGO/WO3 nanocomposite film was characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Raman spectroscopy, X-ray diffractometry (XRD) and electrochemical impedance spectroscopy (EIS). The effects of the added RGO and AuNPs on the electrochemical properties of the AuNPs/RGO/WO3/GCE electrode for sensing HQ and CC were studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Comparative electrochemical sensing results revealed that the sensor that was made of the AuNPs/RGO/WO3 nanocomposite film exhibited much higher selectivity and sensitivity than those of pure WO3 and RGO/WO3 films for the simultaneously sensing of HQ and CC. This sensor exhibited high sensitivity, good linearity, a low detection limit and high selectivity for the simultaneously sensing of HQ and CC.