Samarium-doped borate glass is widely used in solid-state devices due to their suitable refractive index and appealing spectral characteristics. Here, we used the melt quenching technique and characterized the microstructure, optical absorption, electronic transitions and non-linear optical parameters of K2O-borate glass doped with a constant amount of Sm2O3 (1.8 mol %) and different amounts of PbO (0, 5, 10, 15 and 20 mol %), primarily using Fourier-transform Infrared (FTIR) and optical absorbance. FTIR results confirmed the strong influence of PbO on the glass internal structure. Further, inspecting the optical absorption, we found the following results. The optical absorption bands at 401, 475, 935, 1073, 1226, 1369, 1468, 1528, and 1942 nm are recognized to Sm3+ cation's electronic transitions from 6H5/2 (ground state) to 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6H13/2 states respectively. Furthermore, for the PbO-free glass sample, an absorption band we observed at ∼220 nm in the UVC-domain. Moreover, this PbO-free glass sample is transparent in the rest of the UV-regions. A broad absorption band starts to appear with increasing the PbO concentrations in the glass system. The broadening of this band increased with further PbO additions. This band was attributed to Pb2+ cations with 6s2 species that absorb sturdily in the UV-domain. More, the glass sample doped with the highest PbO concentrations (20 mol %) can be considered a UVA transparent material, blocking UVC and UVB. Also, we found the values of Urbach energy, non-linear refractive index, third-order non-linear susceptibility, and refractive index increased for additional PbO contents, which is attributed to the increased disorder in the glass matrix. Furthermore, the results propose that the PbO-free glass sample can be used as UV-transparent material in optical applications. On the other hand, the glass sample that contains the highest PbO concentrations (20 mol %) can be used as a glass filter in some optical applications that permit UVA to pass and block UVC and UVB radiations.