An organic-POMs nanoparticle of PMo9V3/CS was successfully synthesized from chitosan (CS) and H6PMo9V3O40 (PMo9V3) by immobilized method. After characterization, PMo9V3/CS hybrids were determined to possess dual enzyme properties similar to peroxidase and oxidase (KO3). PMo9V3/CS exhibited good kinetic activity towards H2O2 and could catalyze the decomposition of H2O2 to generate * OH and reactive oxygen species respectively. It also showed stability in wide pH range between 3 to 8. Based on the high peroxidase-mimetic and ROS activities, PMo9V3/CS for the first time was used as a nano-material to exhibit antibacterial properties against E. coli (gram negative bacterium). PMo9V3/CS-based antibacterial showed high proficiency in damaging the existing biofilm and preventing formation of new biofilm than H2O2. This performance was a contribution of the CS-mediated membrane destabilization and POM-mediated oxidation of bacteria in the electron transport chain, causing the deformation of rod shape morphology and the decrease of density count of the bacteria. Therefore, PMo9V3/CS shows excellent antioxidant activity and enzymatic-stability for clinic application.