Development of environmentally benign methods for synthesis of nanoparticles is an evolving important branch of nanotechnology. In the present study we report a green method for synthesis of stable silver nanoparticles (SNPs) from aqueous leaf extract of Syzygium alternifolium an endemic medicinal plant to Southern Eastern Ghats. These green synthesized nanoparticles are characterized by using UV-VIS spectroscopy, FTIR, XRD, AFM, SEM with EDAX and TEM. The colour change from yellow to grey is observed upon synthesis and 448 nm peak was obtained from UV-VIS spectroscopic analysis. FTIR spectroscopic studies confirms that phenols and proteins of leaf extract is main responsible for capping and stabilization of these SNPs. Crystallographic studies from XRD indicated the SNPs are crystalline in nature and owing 44 nm size. High resolution and magnification studies with AFM, SEM and TEM analysis revealed that the nanoparticles are spherical in shape having the size range from 7 to 44 nm. EDAX pattern of synthesized SNPs showed 47.28 weight percentage of Ag metal in the sample indicate the purity of sample. Further, the antimicrobial studies of these green synthesized SNPs show high toxicity towards different bacterial and fungal isolates. The results revealed that the selected medicinal plant possess the potentiality towards the synthesis of narrow range nanoparticles also combat with the pathogens.