<p>The purpose of the research presented is to investigate the protective capacities against gamma-ray and X-ray of high-density polyethylene materials reinforced with different concentrations oxide of lead and bismuth. The materials under study were exposed to a range of gamma ray energy levels and their protective efficiency is quantitatively evaluated through the analytical measurement of several parameters, including mass attenuation coefficient, linear attenuation coefficient and half-value layer. The results derived from both theoretical calculations by Phy-x and simulated outcomes by the Geant4 simulation tool demonstrate a commendable level of correlation and consistency, thereby reinforcing the validity of the findings reported in this study. As photon energy increased, the radiation protection efficiency decreased, while as thickness increased, the radiation protection efficiency increased. It is particularly noteworthy that high-density polyethylene composites, reinforced with specific concentrations of lead and bismuth, exhibit superior radiation shielding properties. This remarkable performance can be attributed to the strategic dispersion of heavy metals as well as their associated density characteristics, which together contribute to the effectiveness of these materials in reducing harmful radiation. Finally, the fast neutron removal cross section was also calculated for polymer composites. In conclusion, these findings emphasize the potential of lead–bismuth-reinforced high-density polyethylene composites as promising materials for radiation shielding applications.</p>