The green nanotechnology is a promising and environmentally friendly approach to producing nanomaterials with unique properties. Because of their improved electrical and thermal properties, catalytic activity, and biocompatibility, nanomaterials are very appealing for various uses, such as renewable energy, optics, biomedical applications, and catalysis. With a lower carbon footprint, the green synthesis of nanomaterials utilizes natural reagents, such as herbs, bacteria, fungi, and agricultural waste, rather than hazardous chemicals. Compared to conventional methods, the green synthesis of nanomaterials is very promising due to its low cost and safety for the environment as well as human health. A thorough review of recent research in environmentally friendly manufacturing methods for a variety of nanomaterials, including those based on organic and inorganic materials, is given in this book chapter. It discusses the many applications of nanoparticles including electronics, health care, energy, and the environment.