<p>Nanotechnology is a cutting-edge scientific discipline that combines biology, chemistry, and engineering to modify materials at the molecular and atomic level. Among the different synthesis techniques, green synthesis of nanoparticles has drawn a lot of interest as a sustainable, economical, and environmentally beneficial substitute for traditional physical and chemical procedures. In order to synthesize metal and metal oxide nanoparticles like Ag, Au, Cu, and ZnO, natural reducing and stabilizing biomolecules are produced by using plant extracts, bacteria, fungi, algae, and other biological agents. Because of their unique physicochemical features and high surface-to-volume ratio, these nanoparticles have outstanding antibacterial, antifungal, anticancer, and catalytic activities. The current review focuses on the various biological applications, comparative benefits over traditional approaches, and the mechanics and principles of green synthesis. The antifungal activity against pathogenic species is given particular attention, and green-synthesised nanoparticles show strong efficacy even against fungi that are resistant to drugs. Additionally, characterisation methods like FTIR, XRD, SEM, TEM, and UV-Vis spectroscopy validate the stability and shape of nanoparticles. All things considered, this paper emphasizes how green synthesis provides a sustainable method of producing nanoparticles, bringing nanotechnology into line with environmental protection and biomedical development.</p>