Zinc oxide (ZnO) nanoparticles were synthesized by thermal decomposition method and formation of composite with conducting copolymer via in situ chemical oxidative polymerization. Transmission electron microscopy showed that the nanoparticles with an average diameter of 15-25 nm were dispersed in the copolymer matrix. The comonomer molecules were adsorbed on the surface of ZnO particles and then polymerized to form core-shell nanocomposite. The obtained nanocomposite showed a significant improvement in the thermal behavior as indicated by thermogravimetric analysis. The nanocomposite was also confirmed by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and X-ray diffraction. Room temperature conductivity of nanocomposite was higher than the value obtained for the pure copolymer. Photocatalytic activity of the nanocomposite was evaluated by measuring the degradation of methylene blue dye under UV irradiation.