This research aims to prepare a polymeric composite material from styrene butadiene rubber (SBR) reinforced with lead nanoparticles (Pb-NPs) to make protective shields from gamma rays to protect the healthy tissues of cancer patients while receiving treatment and to protect workers in nuclear reactors and malignant tumors centers. The basic principle is to attenuate the gamma-ray photons emitted by the Cesium source (Cs137) with an energy of 663 keV. The basis for studying the shielding properties after adding the 50,100,150,200, and 300 phr lead nanoparticles. The results showed increased mass density, linear attenuation, and mass attenuation coefficients by 743.712%, 390.47%, and 180.95% with increasing loading levels of Pb-NPs in SBR composites up to 300 p h r. At the same time, the half-value and tenth-value layers decrease by 64% compared with the control sample (without Pb-NPs). The field emission scanning electron microscope (FE-SEM) images show good dispersion and homogeneity of these particles in the rubber matrix, and few agglomerations occur with increasing lead loading. The swelling ratio decreased by 199%, increasing the volume fraction of rubber and cross-link densities by about 7.1% and 14%, respectively. the addition of lead nanoparticles leads to enhanced crystalline properties.