Ellagic acid is a polyphenol found in plant-based foods with health benefits. In this study, valorization of chestnut shell (shell: inner pellicle and peel) to produce ellagic acid by fungal fermentation was investigated. Newly isolated black Aspergillus spp. (A. aculeatus ZGM6, A. japonicus ZGM4, A. niger ZDM2, A. tubingensis ZDM1) were screened to evaluate their potential for fermentation. LC-MS/MS and HPLC-PDA were carried out to identify ellagic acid and its derivatives in the fermentation medium. A. japonicus ZGM4 was found to yield the highest level of ellagic acid and used as the test microorganism to determine optimum fermentation conditions. Optimization studies were conducted by the Plackett-Burman Design followed by the Central Composite Design. Concentrations of lactose and yeast extract and fermentation time were found as effective factors on ellagic acid yield. Fermentation of chestnut shell under the optimized conditions (11.5 g/L lactose, 5.9 g/L yeast extract, 140 h) generated 6-fold increase in concentration of ellagic acid. Chestnut shell can be utilized as a natural source of ellagic acid that could be further enriched by fermentation.