Xanthohumol (XN) is a unique prenylated flavonoid in hops (Humulus lupulus L.) and beer. XN alleviates hyperglycemia and has potential usage in the treatment of type 2 diabetes. In the present study, a series of in vitro experiments were performed to investigate whether XN was an effective inhibitor of α-glucosidase. The results showed that XN inhibited α-glucosidase in a reversible and noncompetitive manner, with an IC50 value of 8.8 μM and that XN inhibited the release of glucose from the maltose in the apical side of the Caco-2 cell monolayer. Fluorescence and circular dichroism spectra results indicated that XN directly bound to α-glucosidase and induced minor conformational changes of the enzyme. These results demonstrated that XN is a promising α-glucosidase inhibitor, which therefore could be used as functional food to alleviate postprandial hyperglycemia and as a potential candidate for the development of an antidiabetic agent.