Abstract <p>A novel class of nanocomposites based on isotactic polypropylene with incorporated C_60/70 fullerenes was investigated. Zinc oxide nanoparticles were embedded using a high-pressure polyethylene matrix as a stabilizing medium, prepared by mechanochemical treatment. The morphological structure and physicochemical behavior of the composite were systematically examined in relation to the introduced hybrid filler system. Thermal stability in nanocomposites were improved over the unfilled polypropylene, owing to the optimization of morphological features and improved compatibility at the filler–matrix interface. SEM analysis revealed a sophisticated entanglement of nanoparticles among themselves and with the polymer matrix, resulting in the formation of a fine-crystalline supramolecular architecture. This newly formed structure, attributed to the interfacial synergy between zinc oxide-based nanoparticles and the C_60/70 fullerene mixture, significantly enhances the mechanical strength and thermal stability of the nanocomposite. It is shown that the obtained isotactic polypropylene nanocomposites incorporating C_60/70 fullerene mixtures and zinc oxide nanoparticles contribute to the possibility of using them in many areas: in elements for converting solar energy into electrical energy (photovoltaic devices), fuel cells, membrane technologies, and the creation of nanometer-scale optoelectronic devices. These findings highlight the potential of the synthesized materials for application in advanced polymer-based technologies.</p>