A bimetallic mixed metal oxide (NiO/CuO) nanocomposite was synthesized, using both chemical and green methods, and investigated. The crystalline nature, phase purity, and size of the nanocomposite were investigated using the X-ray diffraction (XRD) technique. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) examinations revealed about 30 nm size for the composite, which further aided in the deep physical and chemical analysis of the chemical and green route synthesized NiO/CuO composite. The studies also revealed aggregation and hexagonal spherical shape in the nanocomposite. The presence of the Cu, Ni, and O elements in the mixed valence state of the NiO/CuO nanocomposite was revealed using X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) studies. Consequently, the nanocomposite’s potential towards antibacterial and photoluminescence activities were investigated. The NiO/CuO (1 mg/ml) composite demonstrated antimicrobial properties against Escherichia coli, Staphylococcus aureus, and Coagulase-negative staphylococci. The NiO/CuO composite’s ability to inhibit the growth of bacteria was confirmed by the investigation of reactive oxygen species generation. In addition, the PL emission spectra of the synthesized NiO/CuO nanocomposite revealed two visible emission peaks, demonstrating its relevant photoluminescence potential.