<p>Bioactive glass nanoparticles (BGNs) hold significant promise for biomedical applications, particularly in bone tissue engineering and medical implants. However, their interaction with radiation and the need for enhanced multifunctionality remain underexplored. In this study, iron-doped bioactive glass nanoparticles (Fe-doped BGNs) are synthesized with the composition ₍60)SiO₂-(36 − <i>x</i>)CaO-(4)P₂O₅-(<i>x</i>)Fe₂O₃ (<i>x</i> = 0, 1, 2, 4, and 6 mol%) via the sol–gel method to investigate structural, optical, and radiation shielding properties. X-ray diffraction (XRD) revealed that, crystallite size decreased from 48.9 nm (undoped) to 46.3 nm (6 mol%) of Fe₂O₃, while microstrain and dislocation density showed an opposite trend. Fourier-transform infrared (FTIR) spectroscopy confirmed network depolymerization and phosphate bonding, critical for bioactivity. UV–Vis analysis demonstrated a reduced optical bandgap from 3.85 eV to 3.56 eV with increasing Fe₂O₃ content, attributed to Fe³⁺/Fe²⁺-induced electronic state modifications. Radiation shielding parameters, evaluated via Phy-X software, showed superior performance at higher Fe concentrations: the mass attenuation coefficient (MAC) reached 14.690 cm²/g (6 mol% Fe₂O₃) at 0.015 MeV, surpassing undoped samples (11.086 cm²/g). Mechanical analysis revealed enhanced Young’s modulus (72.4 GPa) and hardness (4.85 GPa) for Fe-doped samples, correlating with increased structural density. These findings underscore Fe-BGNs’ dual functionality: optimized bioactivity for osseointegration and exceptional radiation attenuation, positioning them as advanced materials for medical implants in radiation-prone environments. The study provides critical insights into tailoring bioactive glasses for multifunctional biomedical and shielding applications.</p>