Fresh plant extracts of Cassia tora were used for green synthesis of metallic zinc oxide nanoparticles (ZnO NPs) in this study. The efficacy of different parts of the plant was tested against UV-Visible spectrophotometry to conclude the synthesis of nanoparticles. Qualitative characterization of ZnO NPs was achieved by observing the strong absorbance peaks between 302-306 nanometers (nm). Initial confirmation of ZnO nanoparticles formation was achieved by gradual color change from colorless to yellow when the plant extracts were challenged with 1mM solution of Zinc Nitrate at room temperature. The characteristic absorbance peak of ZnO NPs from leaves, stem and roots were 302 nm, 306 nm and 304 nm respectively. The investigation confers that C. tora could be effectively utilized in biological synthesis of nanoparticles.