Naphthol is an environmental pollutant with highly toxic and corrosive. Naphthol can be absorbed by the body easily through the skin, and can cause serious damage to the kidneys and cornea, even cancer. So, it is essential to have a device easy to use, reliable, inexpensive and fast for naphthol detection. In this paper, reduced graphene oxide (rGO) was synthesized using green tea extract as a natural reducer and stabilizer under mild conditions in aqueous solution and decorated with Fe3O4 nanoparticles with a diameter of about 25 nm. The electrochemical sensor for ultrasensitive and selective detection of binaphthol (BINOL) is reported based on the Fe3O4–rGO on carbon paste electrode (CPE). The results demonstrate that BINOL oxidation at the Fe3O4–rGO/CPE sensor can provide a synergistic effect in comparison with CPE and rGO/CPE. The technique of differential pulse voltammetry (DPV) is employed to sensing BINOL with a limit of detection of 78 nM and a linear range between 0.1–100 µM. The sensor also, exhibits high sensitivity (160 µA mM–1), stability as well as good reproducibility. Moreover, this sensor is cost-effective and shows great potential for detection of BINOL in real samples.