The simultaneous, sensitive, and convenient detection of many ions of heavy metal is a difficult challenge. The four primary heavy metal ion contaminants (Cu²⁺, Hg²⁺, Cd²⁺, and Pb²⁺) were detected simultaneously using a unique ratiometric electrochemical sensing approach developed in this article. The construction of platform sensor was applied by a chelating agent of Isatin (2,3-diketo derivative of indole) functionalized reduced graphene oxide (rGO). The as-fabricated catalyst (ISG) exhibited unique features including high porosity and a large surface area, both of which are advantageous for heavy metal ions for adsorption and preconcentration processes. The as-synthesized nanocomposites were analyzed by scanning electron microscopy (SEM, JEOL JSM 6510lv), the interfacial properties of the materials and their crystalline phase were examined. Moreover, Thermal gravimetric analysis was conducted using Shimadzu 50 under N₂ gas flow. The X-ray diffraction (XRD) patterns were carried out to characterize the crystal structure at 2θ range of 5°–70° by a Bruker device. Furthermore, FT-IR patterns were recorded for determination the functional groups in the structure (FT-DATR in wavenumber ranging from 500 to 4000 cm^-. Square wave anodic stripping voltammetry (SWASV), a technique utilized in the determination of metal ions, was used for investigation the electrochemical characteristics of the ISG. The modified electrode indicated enhanced excellent sensitivity and electrochemical catalytic activity towards trace ions of heavy metals. For determination of the target metal ions, several parameters, including time and potential preconcentration, were carefully optimized. For Hg²⁺, Cd²⁺, Cu²⁺, and Pb²⁺, the linear range of the electrode was 5-20 µM under optimized conditions, with low detection limits (LOD) of 1.35, 1.37, 1, and 0.5 µM, respectively.