text: Anthocyanin-rich bilberry extract, a plant-derived antioxidant, has been utilized as a popular supplement for ocular health worldwide. However, it is unclear whether this extract has any biological effect on visual function, and the mechanism for such an effect is completely unknown. In this study, we generated a mouse model of endotoxin-induced uveitis (EIU) that shows retinal inflammation, as well as uveitis, by injecting lipopolysaccharide. We pretreated the mice with anthocyanin-rich bilberry extract and analyzed the effect on the retina. Anthocyanin-rich bilberry extract prevented the impairment of photoreceptor cell function, as measured by electroretinogram. At the cellular level, we found that the EIU-associated rhodopsin decreased and the shortening of outer segments in photoreceptor cells were suppressed in the bilberry-extract-treated animals. Moreover, the extract prevented both STAT3 activation, which induces inflammation-related rhodopsin decrease, and the increase in interleukin-6 expression, which activates STAT3. In addition to its anti-inflammatory effect, the anthocyanin-rich bilberry extract ameliorated the intracellular elevation of reactive oxygen species and activated NF-kB, a redox-sensitive transcription factor, in the inflamed retina. Our findings indicate that anthocyanin-rich bilberry extract has a protective effect on visual function during retinal inflammation.