The objective of this study was to investigate the effects of CuO nanoparticles on the structural, thermal and electrical properties of polyvinyl alcohol (PVA) thin films. The thin films were prepared by a solution casting technique with different weight percentages viz., 0.5, 1.0, 1.5 and 2.0 wt% of CuO nanoparticles in PVA matrix. The fabricated nanocomposite thin films were structurally characterised by Fourier transform infrared spectroscopy and X-ray diffraction, while differential scanning calorimetry indicated the effect of CuO nanoparticles on thermal properties of PVA. The surface morphology of the films was determined by scanning electron microscopy technique. Dielectric properties were analysed using high frequency LCR metre and were found to be dependent on frequency and CuO concentration. Dielectric constant decreased with increase in both frequency and CuO concentration. Dielectric loss increased with frequency increase and decreased with increase in CuO concentration. AC conductivity increased with increase in frequency. PVA-2.0 wt% CuO nanocomposite was found to possess desirable properties such as low dielectric constant and low dielectric loss which makes it a desirable material for use in microelectronics industry.