This study aims to develop large-scale polyvinyl chloride (PVC) nanocomposites for industrial application with power cables. To achieve this goal, PVC/silicon dioxide and PVC/titanium dioxide nanocomposites were fabricated with two different loadings of nanoparticles: 0.3 and 0.6 wt.%, in the presence of a suitable coupling agent that was used to reduce the agglomeration of nanoparticles and enhance the compatibility with polymer matrix. The coupling agent used in this study was the amino silane, and the process followed in the nanocomposites preparation was the melt blending method. The dielectric properties of these synthesised nanocomposites were studied by measuring the AC dielectric breakdown strength under the uniform field, then compared with the simulation results. The relative permittivity ( ɛ r), loss tangent (tan  δ ), and DC electrical conductivity ( σ ) were also measured under frequencies ranging from 20 Hz to 1 MHz. In addition, the internal discharge measurements are performed using the traditional needle-plane configuration with the help of phase-resolved partial discharge (PD) analyser. This technique is used to analyse the PDs activity with respect to the phase angle of the applied voltage. It was found that the dielectric breakdown strength and PD resistance of the prepared samples are increased higher than that of the neat PVC; however, the ɛ r, tan  δ , and σ at 50 Hz are decreased.