Cotton fabrics are usually used for medical purposes, but they can be damaged when exposed to microorganisms. Through modification with carboxymethyl cellulose–polyethylene glycol–ethylene glycol hydrogel/silver/copper oxide (CMC–PEG–EG/Ag/CuO) nanocomposites and subsequent irradiation using an electron beam accelerator, this study proposes an effective method for avoiding bacterial risks on cotton fabrics. The results showed that cotton fabrics loaded with CMC–PEG–EG/Ag/CuO had a low water vapor permeability (WVP) value of 0.09 (0.006% for Ag and 2% for CuO) at a dose of 5 kGy compared with unloaded cotton fabrics (0.33). The tensile strength of the modified cotton fabrics, which had various formulations, was significantly improved with EB irradiation until 25 kGy, exceeding that of the unloaded fabrics. Thermal stability was enhanced by adding CuO nanoparticles up to 2%. The antibacterial activity of the modified cotton fabrics was analyzed by examining gram-negative and gram-positive bacteria. The results showed that the modified cotton fabrics had the highest inhibition zone effect, with 20 and 15 mm for both gram-negative and gram-positive bacteria, respectively. In addition, CMC–PEG–EGs incorporated with 0.006% Ag and 0.012% CuO irradiated at a dose of 5 kGy and 0.006% Ag and 0.5% CuO at a dose of 25 kGy were the most efficient formulations. Meanwhile, a 0.012% concentration of CuO nanoparticles in the formulation was considered appropriate to provide the best antimicrobial activity, as the cost of modifying the fabrics was minimized.