There is an enormous interest in developing safe, cost-effective and environmentally friendly technologies for nano-materials synthesis. In the present study, extracellular biosynthesis of silver nanoparticles was achieved by Epicoccum nigrum, an endophytic fungus isolated from the cambium of Phellodendron amurense. The reduction of the silver ions was monitored by UV-visible spectrophotometry, and the characterization of the Ag NPs was carried out by X-ray diffraction and transmission electron microscopy. The synthesized Ag NPs were exceptionally stable. It was found that an alkaline pH favored the formation of Ag NPs and elevated temperature accelerated the reduction process. Furthermore, the antifungal activity of the Ag NPs was assessed using a microdilution method. The biosynthesized Ag NPs showed considerable activity against the pathogenic fungi. The current research opens a new path for the green synthesis of Ag NPs and the process is easy to scale up for biomedical applications.