The present work is aimed at the development of highly sensitive electrochemical sensor based on immobilization of 1-phenyl-N-(pyridin-2-ylmethyl)ethanamine (PPE) on glassy carbon electrode (PPEGCE) for the simultaneous detection of toxic metal ions of mercury, cadmium and copper, employing electrochemical impedance spectroscopy differential pulse anodic stripping voltammetry and square wave anodic stripping voltammetry. We optimized several experimental parameters such as concentration of the modifier, pH, scan rate, number of cycles, accumulation time, deposition potential and supporting electrolytes for getting robust and intense signals of the analytes. The designed sensor showed nice voltammetric response in media of different pH, demonstrated good percentage recoveries and exhibited remarkable electrocatalytic activity. The results revealed the high sensitivity, stability and absolute discrimination ability of our designed sensor. A wide linear range with very low detection limits for the analytes as compared to reported methods revealed the applicability of our designed sensor as a preferred analytical tool. The limits of detection as low as 0.11, 0.18 and 0.13 nM were obtained for mercuric, cadmium and cupric ions using PPEGCE. These values are lower than the threshold concentration of our selected metal ions suggested toxic by World Health Organization (WHO) and Environmental Protection Agency (EPA). Thus, our results are expected to offer useful guidelines to the environmentalists and health stakeholders to apply measures for the protection of human and aquatic life from water toxins.