Three borate-based glass samples with compositions of xBaO-15Na2O-10Al2O3-(70–2x)B2O3-(x+5)CaO (x = 5, 10, and 15 mol%) were fabricated through the melt-quenching route for the assessment of their structure, optical features, and radiation shielding efficiency. FTIR spectra revealed the coexistence of BO3 and BO4 structural units, whose relative proportions varied with increasing BaO and CaO content. Increasing the BaO and CaO fractions led to a redshift in the UV–Visible spectra, reflecting a higher degree of structural distortion in the borate glass framework. Both direct and indirect optical band gaps showed a decreasing trend (3.804 ± 0.01 to 3.028 ± 0.01 eV and 3.387 ± 0.01 to 2.807 ± 0.01 eV, respectively), attributed to the increased presence of non-bridging oxygens. The observed rise in Urbach energy (0.241 ± 0.001 to 0.346 ± 0.001 eV) suggests an increase in defect concentration and network disorder. Radiation shielding performance was assessed across 0.015–15 MeV, revealing that the linear attenuation coefficient (LAC) decreased with photon energy but increased with BaO content, reaching 67.034 cm−1 at 0.015 MeV for the Ba15Ca20 sample. The effective atomic number (Zeff) varied with energy and composition, attaining maximum values of 23.52, 29.98, and 33.88 for Ba5Ca10, Ba10Ca15, and Ba15Ca20 glasses, respectively, at 0.015 MeV. The half-value layer (HVL) values of the prepared glasses were consistently lower than those of previously reported BaO-SiO2-B2O3 systems, confirming superior attenuation efficiency. The results show that the developed glass system demonstrates excellent potential for multifunctional optical and radiation shielding purposes, such as medical radiation shields, nuclear waste containment materials, and transparent shielding windows in nuclear facilities.