A new ternary nanocomposite of polyaniline (PANI), prussian blue (PB) and zinc oxide (ZnO), i.e., PANI-PB-ZnO was successfully synthesized in one pot process through chemical oxidative polymerization of aniline using ammonium persulfate as oxidizing agent. The morphological studies showed the formation of PB nanocubes and agglomerated quasi-spherical ZnO nanoparticles over PANI matrix, and the elemental composition of PANI-PB-ZnO was analyzed with energy-dispersive X-ray spectroscopy. The XRD measurements reveal the semicrystalline structure of the PANI-PB-ZnO nanocomposite after the polymerization reaction. The various functional groups present in PANI-PB-ZnO were identified using FTIR spectroscopy which confirms the presence of ZnO, PB and PANI in the synthesized ternary nanocomposite. From thermogravimetric analysis, the thermal degradation mechanism of PANI-PB-ZnO nanocomposite was explored and the activation energy (E-A) was calculated from Coats-Redfern plot and was found to be 14.33kJ/mol. 38wt% of PANI-PB-ZnO nanocomposite was obtained as a residue at 800 degrees C indicating the high thermal stability. The bulk ionic conductivity value of the synthesized nanocomposite was found to be 8.509x10(-5-1)cm(-1) at 30 degrees C and 1.22x10(-4-1)cm(-1) at 100 degrees C. The ionic conductivity was found to increase with temperature for the synthesized material which showed an increase in the number of effective charge carriers. The characteristic absorption bands were detected using UV-Vis spectroscopy that confirms the formation of PANI-PB-ZnO nanocomposite. X-ray photoelectron spectroscopy measurements confirmed the valence states of constituent elements in ZnO nanoparticles and ternary PANI-PB-ZnO nanocomposite. I-V studies revealed that hybrid PANI-PB-ZnO nanocomposite has higher conductivity (2.4x10(-4)Scm(-1)) than ZnO nanoparticles (3.5x10(-10)Scm(-1)).