In the present study, a facile and ecofriendly method has been developed for the synthesis of silver nanoparticles from silver nitrate using Asiatic mangrove (Rhizopora mucronata) a natural biopolymer, as a reducing and stabilizing agent. The influence of different parameters such as pH, temperature and reaction time on the synthesis of nanoparticles was studied. The results recorded from UV-vis spectrum, scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray diffraction (XRD) and Atomic Force Microscopy (AFM) support the biosynthesis and characterization of silver nanoparticles. Biosynthesis of silver nanoparticles and activity on clinically isolated human pathogens viz., Gram positive and Gram negative bacteria and fungi were investigated. The synthesized silver nanoparticles had significant antibacterial action on both the classes of bacteria. As the silver nanoparticles are encapsulated with functional group rich mangrove, they can be easily integrated for various medical applications.