A borosilicate barium glass series doped by erbium (III) oxide was fabricated using the conventional melt quenching technique with a melting temperature of 1100 °C and an annealing temperature of 400 °C. The x-ray diffraction pattern confirms that the glass samples are amorphous and have no long-range atomic arrangement. The densities of the borosilicate barium enhanced from 2.9749 g cm−3 to 3.0126 g cm−3 with an increasing Er2O3 substitution ratio. The UV–vis spectrum measurement showed an enhancement in the refractive index of the samples from 2.311 to 2.336. The γ-ray shielding properties of the fabricated glasses were estimated between 0.059 and 1.332 MeV. The obtained results showed an enhancement in the linear attenuation coefficient with increasing the Er2O3 substitution ratio to the borosilicate barium glass at low γ-photon energies while no considerable enhancement was achieved in the high and intermediate γ-photon energies. At γ-photon energy of 0.059 MeV, the linear attenuation coefficient was enhanced by a factor of ≈38%, while this ratio dropped to less than 10% for high and intermediate γ-photon energy. The mentioned results showed that the low concentrations of Er2O3 possess a significant enhancement in optical properties and low γ- ray shielding.