In recent years, nanobiotechnology has gained the immense interest of scientists due to its green, economical, and nontoxic approach. Nonetheless, these green methods are also able to produce nanoparticles (NPs) to a large extent with a high rate of success. The bacteria and fungi are the most commonly used microorganism that satisfied the challenges for the synthesis of NPs by conventional chemical methods. Several methods have been discussed in this chapter mainly covering Cu, Ag, and Au metal NPs, and some of their imperative applications. Moreover, extra- and intracellular methods for microbial NPs synthesis are discussed extensively.