Metal nanoparticles are used often in medicine; however, they are associated with collateral damage. Therefore, an alternative source of nanoparticles, for example plant extracts, which have been used in folk medicine, is required that is both effective and eco-friendly. In this study, we used Lawsonia inermis, Rhamnus fsrangula, Camellia sinensis, and Thymus vulgaris to prepare silver nitrate nanoparticles (AgNPs). The nanoparticles were differentiated by UV-Vis spectroscopy and transmission electron microscopy. Further, the antibacterial and antifungal activity of each AgNPs preparation was examined against different species of microorganisms. A change in color of the plant extracts was considered to indicate formation of AgNPs. AgNPs synthesized using these plant extracts showed significant antimicrobial activity against selected strains of bacteria and fungi. Therefore, these AgNPs prepared using plant extracts are effective and safe for use against these microbes. They also offer important advantages over commercial antibiotics and may prevent the risk of emergence of antibiotic-resistant bacterial strains.