The impact of 0.5–1.5 mol% Er3+ ions on the structural, optical, mechanical, and radiation shielding properties of a borate glass system is investigated in this study. With continuous Er3+ doping, Fourier Transform Infrared spectroscopy established the attenuation in network rigidity because of the change of [BO4] into [BO3] units and Non-Bridging Oxygens (NBOs). This was consistent with iconicity rise and reduction in the average coordination number. The increase in the number of NBOs identified to form localized states within the energy gap was related to the lowering of the bandgap of the glass with Er3+ doping. The decrease in Vicker's microhardness and elastic constants of the glass samples with Er3+ doping was understood by the drop in the network rigidity. MCNP5 and WinXCom codes were used to determine the radiation shielding characteristics of the glasses. The scope of the glasses can be extended for shielding because their features were on par with some commercial shielding glasses.