<p>Imine-based covalent organic framework (COF) nanoparticles were synthesized and incorporated into thin-film nanocomposite (TFN) membranes. Comprehensive structural analyses, including FTIR, PXRD, SEM, TEM, and AFM, confirmed the successful formation of COFs and their uniform integration into the polyamide selective layer, which modified the membrane morphology, surface roughness, and hydrophilicity. Contact angle measurements revealed a notable reduction in water contact angle after COF incorporation, highlighting enhanced surface wettability. Pure water permeability of the TFN membranes improved substantially with COF loading, reaching up to 9.8 (L/m².h.bar) for TFN3 compared to 3.6&#xa0;L/m²h·bar for the pristine TFC membrane. Salt rejection tests indicated that moderate COF incorporation preserved NaCl rejection, while excessive loading introduced structural imperfections that slightly reduced performance. Heavy metal ion rejection experiments, conducted using 1&#xa0;g/L nitrate solutions showed outstanding rejections of Cu²⁺ and Mn²⁺ (&gt; 99%) and meaningfully improved Pb²⁺ removal compared to the TFC membrane, with TFN2 achieving optimum balance (99.2% Cu²⁺, 99.0% Mn²⁺, 96.1% Pb²⁺). Antifouling studies with bovine serum albumin (BSA) further demonstrated improved fouling resistance, with TFN2 showing the highest flux recovery ratio and the lowest irreversible fouling ratio. Overall, COF-based TFN membranes exhibit excellent potential for water purification, with TFN2 providing the best synergy between high permeability, selectivity, and antifouling properties, making it a promising candidate for wastewater treatment and heavy metal remediation.</p>