This study aims to investigate the synergistic effects of graphene, aluminum oxide (Al2O3), and silicon oxide (SiO2) nanofillers on the mechanical and thermal properties of epoxy composites. The objectives were to enhance the performance of epoxy resins by incorporating these nanofillers at varying weight fractions (0.5 %, 1 %, and 1.5 %) using ultrasonication for uniform dispersion. Standard ASTM tests, including tensile, flexural, and impact strength tests, along with thermal conductivity measurements, were conducted to evaluate the properties of the nanocomposites. The results revealed that graphene-reinforced composites exhibited the most significant improvements, with tensile strength increasing by 32 %, flexural strength by 21 %, and thermal conductivity by over 300 % compared to neat epoxy. Alumina and silica also enhanced the composite properties but to a lesser extent. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses showed key differences in the dispersion of nanoparticles and the interactions between the nanofillers and the epoxy matrix, with graphene demonstrating superior interfacial bonding. These findings highlight graphene's exceptional potential for enhancing the mechanical and thermal properties of epoxy composites, making them suitable for applications in thermal management and structural components in advanced engineering fields. The study provides valuable insights into optimizing nanocomposite formulations to achieve multifunctional performance.