The investigation in this article focused on the role of La2O3 on the optical, physical, and radiation protection performance of La2O3-based glasses in the form 21.5SiO2-58.5B2O3-(20−x)ZnO:xLa2O3, where x , ( 0 ≤ x ≤ 10 ) mol%. The melt-quenching process was used to synthesize the glasses under study. Density results increased from 3.174 to 4.754, the values of the ( E opt. indi ) increased from 2.996 to 3.313 and ( E opt. di) increased from 3.364 to 3.689. Several radiation shielding factors have been evaluated to study the attenuation abilities of the ZBSL glasses and for all of them, there is a positive correlation between the mean free path (MFP) values and the incoming photon energy. The effective atomic number, Zeff, values increased for all the energies when La2O3 was employed in place of ZnO. Therefore, of all the competing shielding glasses and regular concrete, ZBSL10 glass is an excellent choice for shielding applications from gamma rays and neutrons. This study should be very beneficial for the design of these glasses or for the fabrication of new glasses for radiation protection. [ABSTRACT FROM AUTHOR]