This study aimed to explore the physical, mechanical, optical, and radiation-attenuation characteristics of borate-based glasses with the composition (70-x)B2O3-28Na2O-2Gd2O3-xBaO (where x = 0, 5, 10, 15, and 20 mol%). The glasses were fabricated via the melt-quenching approach, and their amorphous structures validated through X-ray diffraction analysis. The density of the glasses increased from 2.412 to 3.114 g/cm3 due to the effective incorporation of barium oxide (BaO). The mechanical properties, assessed using the Makishima–Mackenzie model, showed a decrease in the mechanical moduli as the BaO content in the fabricated glasses increased. Optical analysis revealed a 3.048 to 2.807 eV decline in the indirect optical band gap energy and a 2.384 to 2.449 elevation in the refractive index as the BaO loading rose from 0 to 20 mol%, resulting in structural changes within the glass network and the generation of non-bridging oxygens. Additionally, radiation-shielding studies were carried out to determine the mass attenuation coefficient (MAC), half-value layer (HVL), and mean free path (MFP) using the XCOM software, revealing that the incorporation of BaO significantly enhanced the radiation-shielding performance of the prepared glasses, among which the glass with 20 mol% BaO (B-20) was the most effective for gamma-ray shielding through exhibiting high MAC and low HVL and MFP values. Furthermore, the evaluated MAC values were compared with those of recognized shielding materials and other BaO-doped glasses at 0.662 MeV, whereby the comparison verified that the glass with the highest BaO concentration provided the optimum radiation-shielding effectiveness, and is thus appropriate for radiation-protection applications.