A robust ternary heterogeneous electrocatalyst, graphene-based CuS spheres decorated on an exfoliated g -C 3 N 4 sheet, with a sensing capability of the outstanding electrochemical property is developed by using nanoarchitecture and surface engineering strategy. Characterized and used for the detection of furazolidone (FZ). A sensitive electrochemical sensor (CuS-rGO/ g -C 3 N 4 on the surface of the GCE) was prepared in phosphate buffer and studied towards the reduction of FZ using cyclic voltammetry and differential pulse voltammetry. Under optimal conditions, the electrochemical sensor that developed exhibits a good relationship between current and potential, linear range from 0.1 to 336.4 µM with a lower detection limit of 0.0108 µM. The electrochemical studies of ternary heterostructure CuS-rGO/ g -C 3 N 4 /GCE composite have strong electrocatalytic activity while bare GCE has a lower reduction potential response and also shows good reproducibility, stability, and repeatability towards the detection of FZ. In presence of the analyte possessing nitro group or cationic or anionic compounds which are the generally encountered interfering species, no significant changes in the reduction peak response are observed which shows the excellent selectivity of CuS-rGO/ g -C 3 N 4 . Hence, the novel ternary composite, CuS-rGO/ g -C 3 N 4 , shows one of the best platforms of graphene-based material that provides a conductive and stable interface for the electrochemical determination of FZ.