Plant mediated ZnO nanoparticles has now become prominent among other metal oxide nanoparticles as easy to synthesize, cheap and safe method with multiple applications. In present study 10% extract of Ocimum basilicum was used as reducing and capping agent for the synthesis of ZnO nanoparticles with 230 mL of 0.2 M Zinc Acetate dihydrate at room temperature (25oC). The synthesized ZnO nanoparticles were dried at 60oC, calcined at 100oC in oven and finally nanoparticles of weight 10.67g/100 mL of plant extract were weighed. Phytochemical analysis and FTIR characterization of plant extract and ZnO nanoparticles depicted strong presence of important bioactive components in plant extract while weak presence or absence was observed in ZnO nanoparticles supernatant layer. Nanoparticles IR- spectrum showed two prominent sharp peaks at 660.33 and 560.22 cm-1 of C- alkyl chloride and hexagonal ZnO that was totally absent in crude extract spectrum. Further XRD diffractogram illustrated highly crystalline face centered cubic ZnO nanoparticles structure having hexagonal wurtzite geometry with average size 30- 40 nm. Moreover, microbicidal activity of synthesized nanoparticles (100mg/mL) was measured against pathogenic strains and zones of inhibition against Staphylococcus aureus, Escherichia coli and Aspergillus niger were recorded as 1.05mm± 0.137, 36.15mm±0.304 and 24.10mm± 0.05, respectively. Minimum inhibitory concentration for S. aureus and E. coli was calculated same as 312.5µg±0.00 whereas for Aspergillus niger was 5000µg ±0.00. Thus a cheap and ecofriendly plant mediated complete method was developed that can be exploited on large scale synthesis to save the capita of Pakistan used to import antimicrobial drugs.