Nano-biofertilizers are the biologically synthesized nano-fertilizers from the microbes and plants employed in the agricultural fields to promote crop production and protection. For instance, specifically, the plant growth-promoting microbes (PGPM) having significant growth promotion and antagonistic traits, have led to their wide range of applications as nano-biofertilizers. In the agricultural scenario, the soil, crops, microbiome and nano-biofertilizers often influence one another and their ecological systems. The application of these PGPM nano-biofertilizers often promised enhanced soil quality and crop protection during both abiotic and biotic stress conditions through their bioactive compounds. This made the PGPM nano-biofertilizers as key players of yield enhancers and an advantage to the ever-increasing global food demand. However, day by day, nanotechnology being more beneficial and economical, many researchers and agriculturalists are shifting towards their wide range of applications in modern agricultural practices. This challenges the nanoparticles (NPs) dosage, toxicity, and their environmental footprint in the agricultural soils over a long time. This chapter highlights the key features of the PGPM nano-biofertlizers, their type and time of application, their dynamics on plant soil health, and the necessity for better and safer marketing applications of these NPs in the agricultural fields. © 2022, Indian National Science Academy.