One of the important carbon materials, graphene oxide (GO), has several oxygen-containing functional groups. Due to its unique structure, it has attracted increasing interest in multidisciplinary studies of physical and chemical attributes. In this work, Bismuth Oxide nanoparticles (Bi2O3) is prepared and functionalized with graphene oxide nanosheets (Bi2O3-GO). The Bi2O3 and Bi2O3-GO nanocomposite were mixed with epoxy by changing the percentages to 1%, 2.5%, 5%, and 10%. The study used a hyper-pure germanium detector to investigate the attenuation characteristics of the prepared samples. Ba133, Cs137, and Co60 point sources were used at photon energies of 81, 276, 302, 356, and 383 keV for Ba133, 661 keV for Cs137, and 1173 and 1332 keV for Co60. The linear attenuation coefficient, mass attenuation coefficient, half-value layer, and tenth-value layer were estimated to investigate the radiation shielding characteristics of the prepared samples. The linear attenuation coefficient (μ) values varied from 0.45 to 0.88, 0.23 to 0.89, and 0.31 to 0.77 for Ba133, Cs137, and Co60, respectively. The mass attenuation coefficient (μm) values varied from 0.18 to 0.50, 0.19 to 0.50, and 0.15 to 0.50 for Ba133, Cs137, and Co60, respectively. Half-value layer (HVL) values varied from 0.79 to 1.55, 0.78 to 3.07, and 0.9 to 2.26 for Ba133, Cs137, and Co60, respectively. Tenth-value layer (TVL) values varied from 2.61 to 5.16, 2.58 to 10.19, and 2.98 to 7.51 for Ba133, Cs137, and Co60, respectively.