Anticorrosion performance of a clear epoxy coating was enhanced by the incorporation of modified nano-silica into the polymer matrix. The surface of nano-silica was treated with 3-Glycidoxypropyltrimethoxysilane (GPTMS) in order to achieve proper dispersion of nanoparticles. The surface grafting of GPTMS on the nanoparticles was detected using fourier transform infrared spectroscopy (FTIR) and dispersion stability test. Corrosion performance of the coated mild steel specimens was investigated employing electrochemical impedance spectroscopy (EIS) and salt spray test. Incorporation of 4–6 wt% SiO2 nanoparticles possessed the best corrosion performance. The electrochemical results are completely in agreement with the morphological results of the surface obtained from scanning electron microscopy (SEM).