Over the years, due to the remarkable functional properties, the nanoparticles have been widely used and being tested in the treatment and diagnosis of diseases such as cancer, diabetes, etc. The green synthesis of these nanoparticles can be achieved by physical, chemical, and biological methods. Nanoparticles biosynthesis is put forth to be advantageous over chemical and physical methods because it is non or minimally toxic, environmentally friendly, and cost-effective. A green biosynthesis is an approach that connects nanotechnology with plants, microorganisms, waste materials, and biomolecules. The biological methods help to eliminate destructive processing situations, via letting the synthesis at biological pH, room temperature, and simultaneously, affordable price. Among various biological alternatives, medicinal plants and plant extracts seem to be the best options. Plants are the chemical factories of nature, the plant extracts contain various secondary metabolites, and it functions as reducing and stabilizing (capping) agent in bio-reduction reaction to synthesize new nanoparticles. Keeping these points in view, the present article reviews the various synthesis methodologies, key factors, characterizations, usages, and foretold antimicrobial approach in a systematic manner, concentrating on several green pathways for nanoparticles synthesis. © 2020 by the authors.