This work synthesized a new composite by coupling copper sulfide nanoparticles and isothiouronium polyurethane foam to enhance antimicrobial activity. Fourier transform infrared (FTIR), ultraviolet-visible spectra (UV/Vis), point zero charge (pHpzc), acidic and basic sites, iodine number, methylene blue value, energy disperse (EDX), X-ray diffraction (XRD), and scan electron microscopy (SEM) were used to characterize isothiouronium polyurethane@copper sulfide foam composite (ITPU@CuS). The antibacterial activity of ITPU@CuS was tested against Gram-positive (Bacillus cereus) and Gram-negative (Pseudomonas aeruginosa). The biocidal action of ITPU@CuS against the microbial strains was significantly higher at the concentration of 150 μg/ml than at lower concentrations. Also, transmission electron microscopy (TEM) of the ITPU@CuS-treated bacteria was studied. TEM micrographs of the treated bacteria confirmed the bactericidal action of ITPU@CuS by showing malformation action, wrinkling, and bacterial cell wall damage. The obtained composite could be considered to be a promising material aimed at industry, especially in the field of food packaging, where it is effective against pathogenic microbes.