The current study aims to develop polyvinyl chloride (PVC) nanocomposites with enhanced electrical and mechanical properties by incorporating titanium oxide (TiO2) nanoparticles within PVC chains. Different loading of nanoparticles and different nanoparticle surface states were considered. The surface states are unfunctionalised, functionalised using vinyl silane and functionalised using amino silane. The choice of a most suitable surface state was a critical factor that guarantees a good dispersion of nanoparticles and consequently enhances the compatibility between TiO2and PVC matrix. The process followed in the PVC/TiO2nanocomposites preparation, loaded with different wt.% of TiO2nanoparticles, was the solvent method. The dielectric properties measured here were the relative permittivity (ϵr), dielectric loss (tano), breakdown strength (AC and DC under uniform field) and the internal partial discharges (PDs) within insulation cavity. All measurements have been performed under room temperature and at frequency ranged from 20 to 1.0 MHz. Furthermore, the mechanical properties of the samples like elongation, elasticity modulus and tensile strength were also studied. Vinyl silane showed better improvements in both electrical and mechanical performances compared to the amino silane, especially in cases of high weight fractions of TiO2. This is because of the improvement in the PVC-TiO2interfacial region arise from the similarity of polarity and surface tension values of vinyl silane with that of PVC matrix and TiO2nanoparticles.