Chitosan is used in food, medicine, and other fields because of its good biocompatibility, but its solubility restricts its application, and modification treatment can reduce the stability to improve its solubility in different pH solutions. This study investigated the effects of electron beam irradiation (EBI), cold plasma (CP), and their dual modification treatments on the structural, physicochemical, and functional properties of chitosan. The results showed that single EBI, CP treatment, and dual modification treatment did not significantly change the morphological structure of chitosan. Among them, the viscosity and thermal stability of single EBI- and CP-modified chitosan was reduced. Still, the antioxidant and antibacterial properties against Staphylococcus aureus and Escherichia coli were enhanced compared to native chitosan. Meanwhile, the viscosity, molecular weight, and thermal stability of dual-modified treated chitosan were further reduced, and the antioxidant and antibacterial properties were significantly improved compared to EBI and CP modification alone. This study shows that dual modification's effect was better than that of single modification treatment, especially single cold plasma treatment. This will also lead to the diversification of chitosan modification methods and promote its application in various aspects, such as preservation, food additives, functional food ingredients, and packaging materials.