The rise of antibiotic resistance necessitates the development of advanced antibacterial agents. Here, a ZnO-Co3O4 nanocomposite with varying concentrations is synthesized via the sol-gel method. The structural and morphological features of the as-synthesized nanocomposite are characterized using X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy techniques. The composite design enhances antibacterial performance compared to single oxides. The results revealed that ZnO-Co3O4 nanocomposites exhibit concentration-dependent morphology and antibacterial activity. Notably, ZnO-Co3O4 nanocomposites demonstrated superior antibacterial activity compared to pure ZnO. The addition of cobalt oxide decreased the size of the nanoparticles, thereby enhancing their antibacterial activity, particularly against Gram-positive bacteria, compared to Gram-negative bacteria. This enhanced activity is attributed to the increased production of reactive oxygen species and the improved penetration capability of the nanocomposite.