Using a melt-cooling process with the host glass, Dy2O3 (1 wt%, 2 wt%, 3 wt%, and 4 wt%) doped tellurite glasses were produced. A (65–x)TeO2–20B2O3–10Al2O3–5GeO2–xDy2O3 glass system was analyzed by X-ray diffraction. The patterns have a hump at 2θ = 27°–29° and no sharp peaks, indicating that all the glass samples are amorphous. The Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder substance. Differential scanning calorimetry (DSC) at 300–550 °C was used to evaluate the thermal properties of the Dyx glass samples. The glass transition temperature Tg (small endothermic peak), start crystallization temperature Tx and crystallization temperature Tc can all be seen on the DSC thermogram (exothermic peaks). The UV–Vis transmittance and absorption spectra were measured. The optical data show that the values of Egdir, EgInd and EU decrease as the amount of Dy2O3 increases, indicating a narrowing of the tails due to localized states in the forbidden gap. A concentration quenching event occurs when Dy3+ concentrations are above a certain threshold (1%). The addition of Dy2O3 increases glass density, while the addition of other Dy(III) oxides increases sample density. The radiation shielding values change as a consequence of density fluctuation. The sample with the highest amount of Dy2O3 (Dy4) has stronger radiation shielding characteristics; hence, it is superior in terms of shielding outcomes at all energy levels. Such Dyx samples can be used in various forms of ionizing radiation shielding.