AbstractNature and nanotechnology have not yet achieved a lucid correlation in the field of science but together they have exhibited immense potential towards the advancement and modification in future science and technology. Due to the unique properties of nanomaterials like nanoparticles gained considerable importance. Among all the nanoparticles, zinc oxide (ZnO NPs) are greatly utilized in sensors, catalysis, bioscience, etc. Antimicrobial activity by ZnO NPs had more attention by the implementation of nanotechnology for the preparation of ZnO NPs. At present, antimicrobial activity of ZnO NPs using Aegle marmelos (A. marmelos) leaves extract was done. The ZnO NPs subjected to UV-Vis, FT-IR, XRD, SEM and TEM analysis. The presence of phenolic group in extract has the capacity to form ZnO NPs and act as stabilizing agent. Every 5 min interval ZnO NPs was formed which recorded by UV-Vis spectrophotometer. The SEM analysis displayed a fine spherical ZnO NPs and EDAX report showed that the existence of zinc and oxygen in the ratio of 30.51% and 69.49%. The antimicrobial activity of ZnO NPs has high percentage inhibition against A. niger at 1000 ppm. Till now, no research carryout on A. marmelos mediated ZnO NPs and applications towards antimicrobial activity.