The high adsorption capacities of Polyaniline (PANI) and Carbon Nanotubes (CNTs) for heavy metals, combined with the synergistic effect of Magnesium Oxide (MgO), were leveraged to develop a modified Glassy Carbon Electrode (GCE), referred to as MgO@PANI@CNT/GCE, for the accurate detection of Cd²+ and Pb²⁺ ions. A comprehensive investigation of the electrochemical response of the MgO@PANI@CNT/GCE was carried out using Differential Pulse Voltammetry (DPV). A systematic optimisation of the electrochemical parameters, including the pH of the buffer solution, the amount of MgO@PANI@CNT on the electrode surface, and the drying time, was carried out. Under optimal conditions, the MgO@PANI@CNT/GCE sensor showed a linear response in the concentration range from 10-8 to 2.5 × 10-7 M. The lowest detectable concentrations for Cd2+ and Pb2+ were measured as 5 × 10-8 M and 2.5 × 10-8 M, respectively. The sensor exhibited excellent stability and reproducibility, and its practical utility was confirmed through the successful detection of Cd²⁺ and Pb²⁺ in river water samples, highlighting its effectiveness for real-world applications.