A new composite of Hemin, copper oxide nanoparticle, and oxidized g-C3N4 (He/CuO/Oxi-gC3N4) is fabricated and successfully employed for electrocatalysis of the chlorinated Organo-Phosphorous pesticide, Dichlorvos. Hemin (He) is a well-known metalloporphyrin, which has an electroactive center of Fe3+. Pure hemin aggregates easily due to its poor solubility in an aqueous solution and hence is usually composited with other electroactive materials. The composite electrode has been thoroughly characterized including SEM, AFM, FT-IR, Raman spectroscopy, XPS, and Voltammetric techniques for the determination of Dichlorvos in water sample. Herein we have used a composite of Hemin with green synthesized copper oxide nanoparticle, (CuO)-Nps adsorbed on a porous oxidized graphitic carbon nitride surface (Oxi-gC3N4). The obtained linear range for Dichlorvos was found to be 2.5 × 10−10 to 62.5 × 10−10 M with a detection limit of 0.83×10−11 M. The composite electrode performance was further extended for use in real samples like lake water, well water, and tap water containing Dichlorvos. The analysis was carried out based on the standard addition method. Good recovery ranges from 99.0 to 100.0% were observed. Also, the He/CuO/Oxi-gC3N4 showed very good antibacterial activity against gram-positive and gram-negative bacteria.