Post-irradiation studies have been carried out to elucidate the effects of electron beam irradiation on the structural, optical, dielectric and thermal properties of ultra-high-molecular weight polyethylene (UHMWPE) films. The modifications in the optical band gap, activation energy, oscillator strength, and transition dipole moment have been investigated as a function of electron radiation dose using UV-Vis absorption spectra of UHMWPE films. The spectral analysis showed a decrease in both the optical band gap and activation energy, whereas the oscillator strength and the transition dipole moment increased with the increase in electron radiation doses. Further, the dielectric measurements indicated a slight increase in the dielectric constant and the ac conductivity of the UHMWPE films upon electron irradiation. The thermal analysis carried out by differential scanning calorimeter and thermo-gravimetric analyzer revealed that the melting temperature, degree of crystallinity and thermal stability of the UHMWPE films increased, obviously, due to the predominant cross-linking following high doses of electron radiation.