This paper reports the improved gamma radiation attenuation ability of six composite shields prepared using high density polyethylene (HDP) reinforced Al₂O₃, Fe₂O₃, and PbO. The radioactive source ²²⁶Ra was used at different γ-ray energies (0.295, 0.352, 0.609, 1.12, and 1.747 MeV) and the transmitted γ-radiation from the studied shields was detected via a NaI(Tl) detector. The proposed shields' μ, MFP, HVL, TF, RPE, and d_Pb values were determined as a function of γ-ray energy. The experimental results were compared with those calculated using the XMuDat computer program. The measured values of all parameters were consistent with the theoretical results. It was demonstrated that the gamma radiation attenuation capacity of Al₂O₃, Fe₂O₃, and PbO can be significantly enhanced via HDP reinforcement.