Recently, the biosynthesis of metal oxide nanoparticles using plant extract gained great attention compared to other methods. In this work, the green technique was used for the synthesis of copper oxide nanoparticles from the Solanum trilobatum leaf extract. Synthesized copper oxide nanoparticles were characterized by UV, FT-IR, XRD, SEM and EDX to determine the functional group, crystalline size, shape and elemental composition of the synthesized nanoparticles The X-ray diffraction and SEM results confirmed that the synthesized CuO NPs were crystalline in nature and the average size was found to be 38.34 nm. The EDX studies showed that the Solanum trilobatum mediated CuO NPs contain 53.57% of zinc and 46.43% of oxygen. Synthesized CuO NPs were tested against the five pathogenic bacteria and they showed a very good zone of inhibition compared with copper sulphate and plant extract. Especially against Escherichia Coli, Solanum trilobatum mediated CuO NPs performed well inhibitory effect.