Phytosynthesis process of silver nanoparticles using plant extract is simple, cost-effective, and ecofriendly. In this present investigation, we report the green nanoparticles prepared by using stem extract of Cissus quadrangularis and assess the physical and chemical factors such as time duration, metal ion concentration, pH, and temperature that play vital role in the nanoparticles synthesis. The maximum synthesis of silver nanoparticles was attained within 1 h, at pH 8 and 1 mM AgNO₃ concentration, and 70°C. The nanoparticles obtained are characterized by UV–vis spectroscopy. Silver nanoparticles that were synthesized under these conditions show crystalline nature confirmed by X-ray diffraction and show mostly spherical and some rod and triangle shapes with sizes ranging from 37 to 44 nm, which were characterized by scanning electron microscopy. Fourier transform infrared spectroscopy shows that the functional groups are carboxyl, amine, and phenolic compounds of stem extract which are involved in the reduction of silver ions. Thus, synthesized silver nanoparticles show more antibacterial activity against Klebsiella planticola and Bacillus subtilis, which was analyzed by disc diffusion method