Nowadays, there are many studies reported the mycosynthesis of nanoparticles by using rhizospheric and epiphytic fungi but there are a few reports using endophytic fungi. So the present work focuses on the mycosynthesis of nano-Ag using endophytic Aspergillus fumigatus strain EAF102 that evaluated for its antifungal efficiency. The fabricated nano-Ag was initially detected by the brown color and UV-VIS spectroscopy that showed the nano-silver peak at 450nm. The structural and morphological properties of the nano-Ag/Ag₂O were evaluated by SEM, TEM, XRD, FTIR, EDX and TGA analysis. The mycosynthesized nano- Ag/Ag₂O reaction was improved via Taguchi approach and increased 3.9 times larger than the basal reaction condition. The optimized fabrication reaction was set up as following: 1mM of the precursor was added to 25% (v/v) of reductant then this mixture pH was adjusted at 8.0 and the incubation temperature was controlled at 60⁰C under shaking condition (250 rpm). A confirmation test resulted in the maximum nano-Ag/Ag₂O was 44.295 ± 5.27 g/l and its S/N ratio was 33.51± 4.20 dB that considered as a very good agreement with the predicted results. The high activities of mycosynthesized nano-Ag/Ag₂O (11-15 nm) that used as antiphytopathogens were ordered as follows: Alternaria alternate (3.5±0.36), Fusarium moniliforme (2.2±0.45,) Fusarium graminearum (1.5±0.25), Fusarium semitectum (0.58±0.13), Fusarium oxysporum (0.5±0.23), and Phytophthora arenaria (0.45±0.14). Finally, a simple, fast, and eco-friendly method for mycofabrication of nano-Ag/Ag₂O by using endophytic Aspergillus fumigatus strain EAF102 was successfully discovered and improved via this study.