<p>The purpose of the presented research is to conduct investigations into the protective capacities against gamma and neutron radiation of polyolefin materials reinforced with different concentrations of lead and bismuth. During this scholarly inquiry, the efficacy of these composite materials in attenuating gamma and neutron radiation is meticulously evaluated by employing the Geant4 toolkit. The investigated materials are exposed to a range of gamma ray energy levels and their protective efficiency is quantitatively evaluated through the analytical measurement of several critical parameters, including mass attenuation coefficient, linear attenuation coefficient and half-value layer. The results derived from both theoretical calculations and simulated outcomes generated by the Geant4 simulation tool demonstrate a commendable level of correlation and consistency, thereby reinforcing the validity of the findings reported in this study. In the context of neutron energies, specifically focusing on thermal and fast neutrons, and considering material thicknesses of from 1 mm to 1 cm, the number of neutrons that successfully traverse the shielding material is systematically evaluated to determine the overall shielding effectiveness. It is particularly noteworthy that polyolefin composites, reinforced with specific concentrations of lead and bismuth, exhibit superior radiation shielding properties. This remarkable performance can be attributed to the dispersion of heavy metals as well as their associated density characteristics, which together contribute to the effectiveness of these materials in reducing harmful radiation. In conclusion, these findings emphasize the potential of lead–bismuth-reinforced polyolefin composites as promising materials for radiation shielding applications.</p> Graphical abstract <p></p>