Transparent polyethylene terephthalate (PET) substrates were coated with SiO2 and ZrO2 using thermionic vacuum arc (TVA) method for the first time. The melting point of PET is approximately 260 degrees C. Transmittances, thickness, reflectance, and refractive indices of coated PET samples were measured by ultraviolet-visible spectrophotometer and interferometry to characterize their optical properties. Additionally, scanning electron microscopy, energy dispersive X-ray spectroscopy, and atomic force microscopy were used to characterize the coated PET surface morphologies. Our results show that the SiO2-and ZrO2-coated PET samples had lower reflection when the TVA method was used; so, they show antireflective (AR) properties. Moreover, the coating homogeneity and surface roughness are proper for multi-layer AR coatings.