CMC/AAc/ZnO, a novel antimicrobial superabsorbent hydrogel, was prepared via the copolymerization of carboxymethyl cellulose (CMC) and acrylic acid (AAc) by incorporating zinc oxide nanoparticles through gamma radiation. The morphological and structural properties were investigated with the aid of characterization techniques such as scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) analysis. In addition, the swelling behaviour analysis displayed superior pH-responsive performance in distilled water than in saline solutions. XRD confirmed that the ZnO nanoparticles were present in a crystalline state in the polymer matrix. EDX mapping was also used to study the elemental distribution of ZnO, carbon, and oxygen in the nanocomposite. TGA provided evidence of substantial thermal stability; hence, the strength of the material could be very efficient. Besides, the highly effective antibacterial property of CMC/AAc/ZnO against Escherichia coli is confirmed through different assays, such as leaching and nonleaching tests. Unlike conventional methods, this technique avoids the need for chemical crosslinkers or initiators, as gamma radiation induces polymerization and incorporation of the nanoparticles. The resulting nanocomposite exhibits better swelling capacity, thermal stability, and antibacterial activity against Escherichia coli. Such properties make it a promising and novel candidate for biomedical and environmental applications. This research emphasizes the great possibilities of using CMC/AAc/ZnO nanocomposite superabsorbent polymers for manifold biomedical applications and opens up new pathways in the growth of eco-friendly antibacterial material.