Solid insulation materials are the backbone for all kinds of outdoor insulation applications. Environmental stresses degrade every outdoor insulation material with the passage of time. Internal partial discharges and external surface tracking are the two major factors governing the health of outdoor insulation. Best outdoor insulation is the one having lowest level of partial discharge and highest resistance to tracking. Improvement in tracking resistance of polymeric insulation materials has been a concern of many researchers. This study investigates the improvement in partial discharge and tracking resistance of LDPE under the effect of three different nano fillers including SiO2, TiO2, TiO2@SiO2. A very little has been reported on the effect of these nano fillers on the tracking performance of LDPE. TiO2@SiO2 is a novel core–shell nano filler. No study has reported the effect of these core–shell nano fillers on the partial discharge and tracking performance of LDPE. It has been observed in this study that core–shell nano fillers are much more efficient in improving partial discharge and tracking resistance of solid insulation materials than ordinary nano fillers.