In this work, silver nanoparticles were synthesized using Salvia microphylla Kunth leaves extract as reducing agent and stabilizing agent. The effect of reaction time and plant extract amount on the biosynthesized nanoparticles were studied. The UV–Vis spectrum indicated that silver nanoparticles show a characteristic surface plasmon resonance at 427 nm. X-ray diffraction experiments show that the silver nanoparticles have a face-centered cubic crystal structure. The density of nanoparticles increases with increasing extract concentration and reaction time. TEM and SEM observations showed well-dispersed quasi-spherical nanoparticles sized in the range of 15–45 nm. The FT-IR analysis suggested the involvement of phenolic compounds in the reduction and stabilization of silver nanoparticles. Synthesized silver nanoparticles showed good antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Finally, the catalytic properties of silver nanoparticles were demonstrated through the degradation of congo red and methyl orange.