Background: Green synthesis of nanomaterials has been increasingly gaining popularity due to its eco-friendly nature and cost-effectiveness. Leaves of Moringa stenopetala are traditionally used to treat several human diseases. Phytochemical studies has revealed that its alcoholic extracts contains different secondary metabolites such as polyphenols, alkaloids, and flavonoids. Objective: this study was conducted to re-investigate the phytochemical constituents of extracts of Moringa stenopetala leaves and synthesis of silver nanoparticle using polyphenols obtained from this plant leaves as a bio-reducing agents and evaluating its antibacterial activity. The synthesis was carried out at different concentration of silver nitrate precursor and fixed amount of plant extract and vice versa. Materials and Methods: The powdered plant material was subjected to extraction using 90% ethanol solution. After yield calculation, the extracts obtained were subjected to phytochemical screening, synthesis of silver nanoparticles and antibacterial activity tests. The antibacterial activity test was carried on four bacterial strains (Gram-negative bacteria Escherichia coli and Klebsiella pneumonia and Gram-positive bacteria Staphylococcus aureus and Staphylococcus pyogenes). Results and Discussion: the required phytochemical constituents like polyphenol and alkaloid, which are used as a reducer, was confirmed from the plant extracts by chemical methods. Yellowish-brown color development of the plant extracts after treatment with AgNO3 solution indicates formation of AgNP. The Ultraviolet-Visible (UV-Vis) spectroscopic result also shows the successful synthesis of AgNPs. Conclusion: this study confirms that the plant contains important phytochemicals that enables reduction of silver ion into silver metal nanoparticles. The synthesized AgNPs have showed a good antibacterial activity against selected bacterial strains. Keywords: Moringa stenopetala, Polyphenols, Silver nanoparticles, Green synthesis.