In the present study, we examined the effects of rhein on pituitary gland implantation-induced adenomyosis, an animal model which mimics human adenomyosis. Oral administration of rhein dose-dependently attenuated hyperplastic and hypertrophic myometrium and improved adenomyosis. The activation of NF-κB and β-catenin signaling pathway was observed in the ectopic endometria. While, rhein dose dependently inhibited the expressions of p-p65, p-AKT and actived Rac1. As Rac1 activation controlled nuclear localization of β-catenin during canonical Wnt signaling, we found that the degradation complex of β-catenin was improved by rhein. In addition, β-catenin nuclear translocation and its downstream genes were markedly suppressed by different doses of rhein. At the same time, decreased activation of epithelial–mesenchymal transition (EMT)-associated proteins including Snail and ZEB1 was detected in rhein-treated mice, indicating that the activation of Wnt signaling pathway was suppressed by rhein. The in vitro study verified a negative regulation of rhein on β-catenin in stromal cells. Stimulation of IL-1β significantly increased the nuclear translocation of β-catenin and improved its target genes expressions. While, rhein remarkably abolished the enhancement in a dose dependent manner. Taken together, our results demonstrated the ability of rhein to inhibit Wnt/β-catenin activation and its potential use in the treatment of adenomyosis and other abnormal activation of β-catenin −associated diseases.