A simple and effective green approach has been developed to synthesize chitosan/Ag nanocomposites that were successfully employed using kumquat aqueous extract and under supporting of microwave as biological reducing agents. It indicates to be an eco-friendly and rapid green method for the synthesis providing a cost effective and an efficient route for the chitosan/Ag nanocomposites’ synthesis. The shape and size of nanoparticles were conducted in the short time only ~10 min for the conversion of chitosan (polymers) and silver ions into chitosan/silver nanocomposites at power of 80 W in microwave. The prepared chitosan/Ag nanocomposites have been characterized by UV-vis, FTIR, XRD, TEM and EDS. Result showed those chitosan/Ag nanocomposites have been obtained with an average particle size of ~10-20 nm. Moreover, the synthesized chitosan/Ag nanocomposites also showed their efficient antimicrobial activity against on the E. coli bacteria. Thus, this eco-friendly method could be a competitive alternative to the conventional physical/chemical methods used for the synthesis of chitosan/Ag nanocompoites. Since, it has a potential to use in biomedical applications, opto-electronics and medical devices in future.