In recent years, nanoscience and nanotechnology have emerged as a new area of fundamental science and are receiving global attention due to their extensive applications. Conventionally nanoparticles were manufactured by physical and chemical techniques. The recent development and implementation of new technologies have led to a new trend, the nano-revolution unfolding the role of plants in bio- and green synthesis of nanoparticles which seems to have drawn a quite unequivocal attention to the synthesis of stable nanoparticles. Although nanoparticles can be synthesized through many conventional methods, biological route of the synthesis is more competent than the physical and chemical techniques. Biologically synthesized nanoparticles have enjoyed an upsurge of applications in various sectors. Hence, the present study envisions biosynthesis of nanoparticles from plants which are emerging as nanofactories. Hence, the present review summarizes the literature reported thus far and envisions plants as emerging sources of nanofactories along with applications, the mechanism behind phytosynthesis of nanoparticles and the mechanism of antibacterial action of nanoparticles.