In this work, the UVB emission of Gd3+ ions incorporated into the Na2O–Ga2O3–B2O3–Y2O3 glass matrix was thoroughly investigated by varying the concentration of Gd2O3. Photoluminescence measurements revealed a strong and well-defined emission peak at 312 nm, related to the 6P7/2 → 8S7/2 transition of Gd3+ ions under 273 nm excitation. Notably, the emission intensity increased nearly threefold as the Gd2O3 concentration rose from 0.2 to 0.8 mol%. The results were examined using Judd–Ofelt analysis and supported by decay kinetics, infrared spectra, ESR spectra, and DSC studies. The enhancement of luminescence was mainly attributed to reduced phonon losses associated with Ga2O3. However, a decline in emission intensity at 1.0 mol% Gd2O3 was observed, which was ascribed to ion clustering and cross-relaxation processes. Overall, this study demonstrates that tailoring the Gd2O3 concentration provides an effective approach to enhance UVB output in alkali–yttria–gallium–borate glasses. The composition containing 0.8 mol% of Gd2O3 is identified as a promising luminescent material for phototherapeutic applications, particularly in the treatment of skin disorders such as psoriasis and vitiligo, and for use in the fabrication of phototherapy devices.