In this report, the polyaniline (PANI)/ZnO nanocomposite system exhibits superior degradation of methyl orange and methylene blue under visible light condition, due to the intermolecular interaction between conducting PANI sponsoring more number of electrons to the conduction band of ZnO nanoparticles. The pure ZnO and the different mole ratios of PANI into ZnO catalysts were prepared by precipitation followed by sonication process. The bandgap of the nanocomposite system revealed in the red region was estimated by Tauc plot. The X-ray diffraction results indicate that the high quantity of PANI into ZnO system reduces the crystallite size and also the crystallinity of the materials. On comparing with the other prepared materials, PZ1.5 illustrated higher degradation of methyl orange and methylene blue. The reason for high catalytic activity and their mechanism of visible light activities were discussed in this paper.