This study focuses on the synthesis of zinc and copper oxide nanoparticles using green methods by plant extracts. The resulting metal oxides were analyzed using FT-IR spectroscopy, TGA, TEM, zeta potential and assessed for their efficacy as pigments based on properties such as Hydrogen Ion Concentration, Oil absorption, Moisture Content, Fineness of grinding, Bleeding, and loss on ignition. The results confirmed that the prepared ZnO and CuO nanoparticles exhibited the formation of nanoparticles in the range of 10–40 nm with potential as pigments. Two paint formulations incorporating these nanoparticles and silicon resins as binders were tested for physico-mechanical attributes, chemical resistance, heat resistance, and corrosion resistance of the dry paint films. The study found that the films containing the prepared oxides demonstrated excellent performance, with no damage or color alteration observed after exposure to temperatures up to 500 °C. Moreover, the paint films containing ZnO nanoparticles showed superior efficiency after a 500 h salt spray test compared to those with CuO nanoparticles. These findings suggest that the synthesized mixed oxide nanoparticles are promising candidates for heat-resistant pigment applications.