A simple yet highly effective approach for the massive production of AgCl/graphene hybrid nanoparticles is described. The use of poly(diallyldimethylammonium chloride) (PDDA), a typical cationic polyelectrolyte, to stabilize the graphene sheets in situ was the key to achieve the goal. AgCl nanoparticles having an average diameter of ca. 500 nm combined firmly with the PDDA-stabilized graphene sheets were produced in large amounts. New insights into the unique photocatalytic properties of the PDDA-stabilized AgCl/graphene hybrid nanoparticles were obtained through analysis of the resultant samples by using X-ray photoelectron spectroscopy together with other suitable analytical methods.