In this study, gold nanoparticle-decorated graphene nanoribbons were prepared using thiol bridge. The obtained nanomaterials were characterized by transmission electron microscopy (TEM) and X-ray photoelectron microscopy, and they were used for modifying the surface of glassy carbon electrode (AuNP-GNR/GC), which is characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The electroanalytical analysis of the AuNP-GNR/GC electrode was performed. The content of an azo dye, Sudan I, was determined by differential pulse voltammetry. Optimum conditions for Sudan I determination were specified; accordingly, the lower detection limit was found to be 1 nM (S/N = 3) over the concentration range of 0.01-75 mu M (R-2 = 0.9964). The accuracy and precision of the developed method were confirmed by intra-day and inter-day measurements. The effects of 1000 mu M Na+, K+, Mg2+, Cl-, Cd2+, Pb2+, Fe3+, Ni2+, Zn2+, Al3+ ions, and glucose, glycine, ascorbic acid, dopamine, and uric acid, which are possible interferants, were investigated. The interference was in the range of -4.71 to +4.02% and acceptable. Regarding actual samples, tomato sauce, ketchup, and hot sauce purchased from the markets were analyzed using the standard addition procedure. The recovery of spiked samples was observed to be between 95.3 and 104%.