In recent decades, the increasing release of industrial effluents has intensified heavy metal contamination in aquatic systems, particularly with lead (Pb²⁺) and cadmium (Cd²⁺), both of which are highly toxic, non-biodegradable, and bioaccumulative. Addressing this challenge requires sustainable, cost-effective, and eco-friendly adsorbents. This study reports the green synthesis of ZnO nanoparticles using green tea extract and their subsequent incorporation onto biochar obtained from orange seed biomass that prepared by pyrolysis at 500 OC. The composite was systematically characterized using Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Dynamic light scattering (DLS), and Zeta potential analyses. Results confirmed the successful embedding of ZnO nanoparticles within the biochar matrix, yielding a highly crystalline hybrid with abundant surface functional groups. Batch adsorption experiments were performed to evaluate the removal efficiency of Pb²⁺ and Cd²⁺ under varying parameters, including pH, dosage, initial concentration, and temperature. Optimal conditions (pH 7, 2 g adsorbent dosage, 15mg/L initial ion concentration and 45 OC) achieved removal efficiencies of 99.1% for Pb²⁺ and 98.2% for Cd²⁺. Adsorption behavior was best described by the Langmuir isotherm model, with high correlation coefficients (R² = 0.9943 for Pb²⁺and 0.9912 for Cd²⁺), indicating monolayer adsorption on homogeneous surfaces. The findings demonstrate that ZnO nano composites –biochar derived from agricultural waste represent an efficient and sustainable adsorbent for heavy metal removal, aligning with green chemistry principles and offering a promising alternative for wastewater treatment applications.