The present work novelty is to develop a new γ-ray shielding material based on the cheap coating polyester sealer reinforced by ferric oxide. The morphology of the newly fabricated polyester-based composites as well as the elemental chemical composition were investigated utilizing the scanning electron microscope and energy-Dispersive X-ray spectrometer. Furthermore, the γ-ray shielding properties were simulated utilizing the Monte Carlo simulation and the results were affirmed using the experimental measurements. The obtained data depicts that the substitution of 50 wt% polyester by Fe2O3 compounds enhances the linear attenuation coefficient from 0.218 cm−1 to 0.553 cm−1 (at 0.059 MeV), from 0.091 cm−1 to 0.108 cm−1 (at 0.662 MeV), and from 0.067 cm−1 to 0.079 cm−1 (at 1.252 MeV). The enhancement in the linear attenuation coefficient values enhances the radiation protection efficiency accompanied by a reduction in the half-value thickness and the transmission factor of the fabricated composites.