A green, sensitive and convenient electrochemical sensor was fabricated for the determination of Sudan I utilizing the excellent properties of a poly(ionic liquid)–graphene nanocomposite. Compared with a glassy carbon electrode (GCE), the modified electrode significantly enhanced the oxidation peak current of Sudan I. This increase in electrochemical response was attributed to the positive charge of poly(ionic liquids) which facilitates the accumulation of Sudan I and the network structure of the poly(ionic liquid)–graphene nanocomposite prepared by electrochemical reduction. Under optimized experimental conditions, the oxidation peak currents of Sudan I were linear to their concentrations in the range of 6.86 × 10⁻⁸ to 8.79 × 10⁻⁶ mol L⁻¹ and the limit of detection of 2.3 × 10⁻⁸ mol L⁻¹ was obtained. Finally, the proposed sensing method was successfully employed to detect Sudan I in food products such as chili powder and ketchup with satisfactory results.