An antibacterial wound dressing hydrogel was synthesized from biopolymers and a semiconductor nanomaterial by gamma irradiation, and applied in a simulated environment. Polyvinyl alcohol (PVA)/agar hydrogel was chosen due to its biocompatibility and good swelling to absorb wound exudates and make a moist environment to accelerate the wound healing process. Zinc oxide nanoparticles were synthesized and combined with the hydrogel due to their antibacterial activity as a wound dressing aid and the hydrophilic nature to enhance swelling capacity by facilitating water flow in the hydrogel. Hydrogel samples based on PVA/agar containing low amounts of zinc oxide nanoparticles were prepared by gamma irradiation to meet all the requirements of a wound dressing. Water absorption, swelling behavior and pH sensitivity were studied and showed an excellent water swelling capacity. Scanning electron microscopy (SEM) and UV–, Vis spectroscopy analyses were employed, where dispersion state of nanoparticles played a key role. Antibacterial activity mechanisms and the resistance to gram-positive bacteria were tested by the disk diffusion method, and the developed hydrogel revealed resistance against gram-positive bacteria. A cone and plate rheometer was used to capture the rheological response of hydrogel. Reduction in viscosity and elastic modulus was due to increasing the amount of zinc oxide nanoparticles. Analyses on mechanical properties approved that hydrogels had enough strength for wound dressing to resist tear once stretched.