The impact of electron beam radiation on the blend of linear low-density polyethylene (LLDPE) and polydimethylsiloxane (PDMS) rubber at different doses from 50 to 300 kGy has been investigated. The irradiated sheets were examined for their morphology, gel content, thermal stability, melt behavior, and electrical and dielectric properties. The radiation treatment has reduced both the melting point and crystallinity of base polymers and their blends because of chain scission. As observed, 100 kGy doses of irradiated blend and 3 wt % of loaded nanosilica composite showed comparatively good thermal stability. The phase morphology of the LLDPE: PDMS rubber blend showed a honeycomb-like design before irradiation because of two-stage morphology, which prominently changed into a solitary stage after electron beam irradiation. This is because of intermolecular cross-link arrangement inside the singular parts, just like cross-linking development at the interface. From the AQFESEM study, it is observed that the stacking of nanosilica particles within the blend matrix is greatly reduced after electron beam irradiation. The addition of nanosilica within the blend increased the electrical conductivity and dielectric permittivity. The dielectric breakdown strength has been observed to be the highest for 3 wt % loaded nanocomposite and its irradiated sample. The result indicates that the nanocomposite can be utilized for high-voltage cable applications in indoor and outdoor fields.