Nanoparticles are nano-sized materials that can be widely used in fields such as medicine, pharmacology, and industry. The use of natural and easily available materials in nanoparticle synthesis is preferred because it is economical. Plants are extremely suitable for the synthesis of nanoparticles due to their natural and easy availability and the large number of components they contain with different properties. For this purpose, silver nanoparticles and zinc nanoparticles (AgNPs and ZnNPs), two different nanoparticles were synthesized from an edible plant, watercress (Nasturtium officinale). SEM (Scanning electron microscopy), SEM-EDX (Scanning electron microscopy-Energy dispersive X-ray), UV-VIS spectroscopy, XRD (X-ray crystallography), and FTIR (Fourier Transform Infrared Spectrophotometer) analyses of these nanoparticles were performed. In addition, the antimicrobial effects of these synthesized nanoparticles were determined by the disk diffusion method. As a result, nanoparticles obtained from Nasturtium officinale were effective on gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa), gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), and fungi (Candida albicans). In particular, AgNPs with broad-spectrum antimicrobial activity were obtained from the watercress. While ZnNPs showed inhibition effects of 49% on K. pneumoniae, 51% on S. aureus, and 62% on C. albicans, AgNPs showed inhibition effects of 93% on P. aeruginosa, 87% on S. aureus, 81% on E. coli, 80% on C. albicans, 72% on K. pneumoniae, and 56% on S. pyogenes. Thus, it has been shown that Nasturtium officinale can be used effectively in the production of new biotechnological products, especially with antimicrobial properties.