The synthesis of metal and semiconductor nanoparticles is an expanding research area due to the potential applications in the development of novel technologies. In this work reports novel biosynthesis of zinc oxide NPs by rhizome extract of plantB. ciliata. The biosynthesized zinc oxide NPs were characterized various techniques using UV-Vis, FTIR, XRD, DLS, SEM and EDX. UV-Visible absorbance spectrum of ZnO NPs exhibited the absorbance band at 340 nm. The XRD data showed the crystalline nature of the nanoparticles. DLS shows average particle size was around 30 nm. Morphology observed by SEM analysis confirming the flower shaped nanoparticle and EDX spectrum presence of Zn and O in the synthesized NPs. The synthesized ZnO NPs showed antimicrobial effects against Gram negative microorganisms with lowest MIC value recorded as 6.25 mu g/mL. Free radical scavenging capacity of zinc oxide nanoparticles were valued using ABTS and DPPH assay with changing the nanoparticles concentration, which showed scavenging activity with IC50 = 63.8 and 118.7 mu g/ mL(-1)respectively. ZnO NPs showed a remarkable selective cytotoxicity against the Human Cervical cancer (HeLa) and Human colon cancer (HT-29) cell lines. The synthesis of ZnO nanoparticles fromB. ciliatarhizome extracts by green synthesis and determination of the bioactivity of these nanoparticles were reported for the first time in this work.