Abstract: Flavonoids are widely existed in plants and herbs, which have a variety of pharmacological activities. Recent studies have shown that they can exert anti-inflammatory, antioxidant, and chemopreventive effects by regulating various signaling pathways. In this paper, we focused on the aryl hydrocarbon receptor, which plays an important role in drug metabolism, immunomodulation, and chemoprevention. After a systematic review of the functions and regulation modes of aryl hydrocarbon receptor, we summarized the agonistic or antagonistic effects of different flavonoids on aryl hydrocarbon receptor and elaborated their anti-tumor, anti-ulcerative colitis, and anti-atopic dermatitis effects by activating aryl hydrocarbon receptor through unique mechanisms. Furthermore, the potential prospects and limitations of flavonoids in the treatment of the above diseases were also presented.