Moringa oleifera leaf extract has garnered significant attention for its potential as a green reducing and stabilizing agent in nanoparticle synthesis. This biogenic synthesis route is cost-effective, eco-friendly, and free from toxic by-products. In this study, metal oxide nanoparticles, including copper oxide (CuO), zinc oxide (ZnO), silver oxide (AgO), and manganese oxide (MnO), were synthesized and characterized by using X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy to determine their size, morphology, and chemical composition. The antibacterial activity of these nanoparticles was evaluated against pathogenic bacteria, demonstrating their potential for biomedical applications. Characterization confirmed the successful synthesis and crystalline structures of the nanomaterials. The average particle sizes of CuO, ZnO, AgO, and MnO nanoparticles were 44.70 nm, 27.04 nm, 37.11 nm, and 36.04 nm, respectively. Antibacterial assays revealed strong inhibitory effects against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, with the highest activity observed for Ag and CuO nanoparticles. Inhibition zones were measured up to 16.11 mm for E. coli and 14.8 mm for S. aureus. These results suggest that green-synthesized nanoparticles from Moringa oleifera extracts are promising antibacterial agents, offering a sustainable alternative to conventional antibiotics.