A tung oil-based acrylated-alkyd resin was synthesized from tung oil, phthalic anhydride, and isobornyl acrylate (IBOA) via an alcoholysis, polyesterification and Diels–Alder reaction with different molar ratios of tung oil and IBOA. The resins were cured at room temperature, and the resulting films were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, atomic force microscopy, thermogravimetric analysis, and differential scanning calorimetry. With the presence of six-membered rings in the polymeric matrix due to the increased content of IBOA, the acrylated-alkyd resins exhibited improved performance characteristics, including mechanical strength, pencil hardness, heat resistance and water resistance.