This paper describes the green synthesis, optimization, and characterization of silver nanoparticles (AgNPs) using Melissa officinalis L. leaf extract via ultrasound, with a total phenolic content (TPC) of 135.22 mg GAE/g ethanol and a total flavonoid content (TFC) of 3.733 mg QE/g ethanol. We used response surface methodology (RSM) with Design-Expert software to carefully optimize synthesis parameters, including the extract-to-silver nitrate volume ratio, AgNO₃ concentration, pH, and temperature. A volume ratio of 0.5, an AgNO₃ concentration of 5 mM, a pH of 8, and a temperature of 60°C were found to be the best conditions for getting the most nanoparticles. A unique surface plasmon resonance (SPR) peak at 420 nm in UV-Vis spectroscopy confirmed the synthesis of nanoparticles. Scanning electron microscopy (SEM) morphological analysis revealed predominantly spherical particles with an average size of 30 nm, while energy-dispersive X-ray (EDX) spectroscopy indicated a silver content of 45.3%, accompanied by plant-derived capping agents including carbon, oxygen, and trace elements. These findings suggest a successful biosynthesis of silver nanoparticles, highlighting the potential of using plant extracts as eco-friendly reducing agents. Further studies could explore the antibacterial properties of the synthesized AgNPs and their applications in various fields such as medicine and environmental remediation. The antimicrobial test showed that it was very effective against harmful microorganisms, with a peak inhibition zone of 25 mm against Escherichia coli. These results show that M. officinalis-mediated AgNPs could be useful as antibacterial agents. They provide a durable and environmentally friendly solution for applications in food, cosmetics, medicine, and the pharmaceutical industry.