This study presents a new insight into transition metal oxide (TMO) doping in bismuth silicate glasses, revealing unprecedented dual-functionality optimization for optical transmission and γ-ray shielding applications. Through a systematic exploration of 1 mol% doping with V₂O₅, TiO₂, Cr₂O₃, Fe₂O₃, CuO, MnO, CoO, or NiO via melt-quenching synthesis, we discovered that TMO incorporation maintains the amorphous glass network while strategically modifying physical and optical properties. Our findings reveal a previously unexplored nonlinear relationship between dopant choice and optical energy gaps, with NiO-doped glass demonstrating superior values. Using Photon Shielding and Dosimetry (Phys-X/PSD) computational analysis, we establish for the first time that these TMO-doped bismuth silicates outperform commercial lead-containing Schott glasses in mass attenuation coefficients (MAC), offering an environmentally friendly alternative with enhanced radiation shielding capabilities. The NiO-doped composition (Bi₂O₃-SiO₂-NiO) emerges as an optimal formulation, delivering the unique combination of high optical transmission and exceptional γ-ray attenuation required for next-generation protective windows in nuclear facilities, medical imaging, and other high-radiation environments. This work provides critical insights into composition-property relationships, advancing the development of multifunctional materials that eliminate the traditional trade-off between optical clarity and radiation protection.