This paper describes a new strategy for the determination of 2,4,6-trichlorophenol (TCP) by using a poly(bromocresol purple)/electrochemically reduced graphene oxide composite film modified glassy carbon electrode (BCP/erGO/GCE). Field emission scanning electron microscopy (FESEM), Raman scattering spectra, X-ray photoelectron spectroscopy (XPS) and electrochemical methods were used to characterize the hybrid film. The BCP/erGO/GCE displayed excellent electrocatalytic activity for the oxidation of TCP without any pretreatment. Under optimum conditions, wide linear ranges of 5.0 × 10⁻⁸ to 1.0 × 10⁻⁶ M and 1.0 × 10⁻⁶ to 1.3 × 10⁻⁴ M were obtained for TCP, and the low detection limit was 5.0 × 10⁻⁹ M. The BCP/erGO/GCE also exhibited a good reproducibility and excellent stability. As a demonstration, the method was applied to determine TCP in real water samples.