This study focuses on the fabrication of a novel sensing platform on a screen-printed carbon electrode, modified by a combination of hydrothermally synthesized iron dioxide (ε-FeO) nanoparticles and Chitosan (CS) biopolymer. This unique organic-inorganic hybrid material was developed for Electrochemical Impedance Spectroscopy (EIS) sensing, specifically targeting heavy metal ions that include Hg, Cd, as well as Pb. The investigation encompassed a comprehensive analysis of various aspects of the prepared FeO and CS/ε-FeO nanocomposites, including phase identification, determination of crystallite size, assessment of surface morphology, etc. CS/ε-FeO was drop-casted and deposited on the Screen-Printed Electrode (SPE). The resulting sensor exhibited excellent performance in the precise and selective quantification of Hg, Cd, and Pb ions, with minimal interference from other substances. The fabricated sensor exhibits excellent performance as the detection range for Hg, Cd, and Pb ions linearity is 2-20 μM, sensitivity, and LOD are 243 Ω/ μM cm and 0.191 μM, 191 Ω/μM cm, and 0.167 μM, 879 Ω/ μM cm, and 0.177 μM respectively. The stability of the CS/ε-FeO/SPE electrode is demonstrated by checking its conductivity for up to 60 days for Hg, Cd, and Pb ions. The reusability of the fabricated electrode is 14 scans, 13 scans, and 12 scans for Hg, Cd, and Pb ions respectively. The findings indicate the successful development of an innovative CS/ε-FeO electrode for the EIS sensing platform. This platform demonstrates notable potential for addressing the critical need for efficient and sensitive EIS sensors capable of detecting a range of hazardous heavy metal ions, including Hg, Cd, and Pb.