In recent years, the focus on nanoparticles has been steadily rising due to their increasing potential in health care applications, while plants have proved to be a great asset to synthesize stable and safe nanoparticles, as they are rich in phytochemicals such as polyphenols, flavonoids, and alkaloids, which act as natural reducing and stabilizing agents, thus synthesizing nanoparticles without the need for hazardous chemicals, rendering them eco-friendly and safe for further exploration for their therapeutic use. This chapter outlines the green synthesis of nanoparticles using plant extracts as a superior form of nanoparticle synthesis, which is eco-friendly, cost-effective, and biocompatible; the characterization techniques that emphasize the influence of size and morphology of nanoparticles on the biological activity; and potential therapeutic activities such as wound healing, neuroprotective, antimicrobial, antioxidant, antiparasitic, and anticancer with some of the formulation advancing to clinical trials. It highlights their applications in medicine as diagnostic tools or as innovative drug delivery systems that enhance solubility, bioavailability, and targeted delivery of therapeutic agents. By integrating the advantages of nanotechnology and phytochemistry, this chapter provides an overview of current knowledge and identifies future research directions to further advance the clinical and industrial translation of plant-based nanoparticles.