Nanotechnology is a multidisciplinary field that evolved within the past few decades and played a substantial role in the environment, industry, agriculture, and pharmacology. Nanoparticles are generally classified based on their dimensionality, morphology, composition, uniformity, and agglomeration. The shape, and morphology of nanoparticles play an essential role in their functionality and toxic effect on the environment and humans. In this review, we discuss the biosynthesis of nanoparticles from microbes. For the biological synthesis of nanoparticles, microbes have been exploited all over the globe. Microbes like bacteria, fungi, and yeasts are mostly preferred for nanoparticles (NPs) synthesis because of their fast growth rate, easy cultivation, and their ability to grow at ambient conditions of temperature, pH, and pressure. Applications of Nanoparticles is a field of research with tremendous prospects for the improvement of the diagnosis and treatment of human diseases. Microbial nanoparticles are found to have vigorous antibacterial activities. The nanoparticles' efficiency is probably due to their larger surface area for enhanced interaction with the micro-organisms. Nanoparticles adhere to the cell membrane and further penetrate inside by interacting with DNA, thereby interfering with the replication process or may attack the respiratory chain of pathogens. A similar bactericidal mechanism of silver nanoparticles obtained from endophytic bacterium Bacillus cereus was observed against pathogenic bacteria like Salmonella typhi, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Pseudomonas aeruginosa.