<p>Fabrication of CuO/ZnO nanocomposite (NC) via the green method is an easy and environmentally friendly process. In this research work, CuO/ZnO NC were fabricated using <i>Jasminum mesyni</i> (<i>J. mesyni</i>) leaf extract, which acted as a reducing and capping agent. The prepared NC was characterized by Ultraviolet–visible (UV–VIS) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and Energy dispersive X-ray (EDX). Morphological imaging of the synthesized nano-product through TEM revealed spherical to quasi-spherical particles. XRD established the crystallinity of the synthesized NC, having an average crystallite size of 16&#xa0;nm. EDX spectrum indicated the existence of oxygen, copper, and zinc in the product. After characterization, the synthesized CuO/ZnO NC was tested for photocatalytic and antibacterial activity. The photocatalytic experiment showed the degradation of methylene blue (MB) in 40&#xa0;min.&#xa0;The synthesized nano-product demonstrated good photocatalytic activity under sunlight irradiation.&#xa0;The bactericidal activity of CuO/ZnO was tested against three gram-positive (<i>B. subtilis, S. aureus,</i> and <i>S. pyogenes</i>) and three gram-negative (<i>P. mirabillis, E. coli, and P. aurginosa</i>) bacteria at various concentrations. IC₅₀ values of the bactericidal activity of the prepared NC were also calculated for each pathogenic bacteria. The results of antibacterial activity revealed an increase in antibacterial activity with increasing concentration.</p> Graphic Abstract <p></p>