(a) adding while heating and stirring, a chlorhexidine solution dropwise into a hyaluronic acid solution to perform a complexation reaction therebetween thereby producing a reaction solution, wherein the hyaluronic acid solution comprises a first solvent selected from any one of water, formamide, DMSO, and DMF, and wherein the chlorhexidine solution comprises a second solvent selected from any one of formamide, DMSO, and DMF, and

(b) separating a product from the reaction solution obtained in step (a), and drying the product to a solid form to obtain a water-soluble chlorhexidine antimicrobial agent, wherein the drying comprises freeze-drying or spray-drying, and wherein the agent is hyaluronic acid chlorhexidine.