Citrus unshiu (C. unshiu) Markovich were dried peel of mandarin orange, of which fresh fruit was one of the famous foods in Korea and Eastern Asia. In the oriental medicine, C. unshiu peel was known to have a diuretic effect and to strengthen spleen function. Recently, natural flavonoids of C. unshiu peel have been investigated. In this study, C. unshiu peel extract containing flavonoid-glycosides was cultured with Schizophyllum commune (S. commune) mycelia producing ${eta}$-glu- cosidase and its biological activities were investigated. ${eta}$-glucosidase of S. commune mycelia converted the flavonoid-glycosides (rutin and hesperidin) into aglycones (naringenin and hesperetin). Fermented C. unshiu peel extract compounds were analyzed by HPLC system. The photoprotective potential of fermented C. unshiu peel extract was tested in human dermal fibroblasts (HDFs) exposed to UVA. Fermented C. unshiu peel extract extract also showed notable in vitro anti-inflammatory effect on cellular systems generating cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) metabolites. Also, UVB-induced production of interleukin-$1{alpha}$ in human HaCaT cells was reduced in a dose-dependent manner by treatment with fermented C. unshiu peel extract. These results suggest that fermented C. unshiu peel extract may mitigate the effects of photoaging in skin by reducing UV-induced adverse skin reaction.