Hydrogels have likely not made widespread penetration in biomedical engineering work due to several key hurdles such as poor mechanical strength and non-existent antimicrobial properties. A new semi-interpenetrating polymer network (Semi-IPN) hydrogel was prepared by interpenetrating carboxymethyl chitosan (CMCH) with acrylamide (AM) and maleic acid (MA) by covalent bond crosslinking enhanced by ionic (carboxylic–Fe³⁺) secondary crosslinks. These hydrogels show a good tensile stress of about 1.44 MPa as well as outstanding antibacterial activity against Staphylococcus aureus and Gram-negative E. coli because of CMCH.