In recent times, plant-mediated synthesis of nanoparticles has garnered wide interest owing to its inherent features such as rapidity, simplicity, eco-friendliness and cheaper costs. For the first time, silver nanoparticles were successfully synthesized using Phyllanthus niruri leaf extract in the current investigation. The silver nanoparticles were characterized by UV–Vis spectrophotometer and the characteristic surface plasmon resonance peak was identified to be 423 nm. The morphology of the silver nanoparticles was characterized by scanning electron microscopy (SEM). The size of the silver nanoparticles was found to be 10-50 nm, with an average size 15 nm.  FTIR analysis was done to identify the functional groups responsible for the synthesis of the AgNPs. The antibacterial potential of synthesized AgNPs was compared with that of aqueous extracts of P.niruri by well diffusion method. The AgNPs at 50µl concentration significantly inhibited bacterial growth against A.hydrophila (16 ± 0.09 mm). Thus AgNPs showed broad spectrum antibacterial activity at lower concentration and may be a good alternative therapeutic approach in future. Keywords: Phyllanthus niruri, AgNps, Aeromonas hydrophila, Antibacterial Activity.