Ricinus communis, belongs to the family Euphorbiaceae, has been known as medicinal plants for treatment of inflammation, tumors, antidiabetic, hepatoprotective and laxative. Compared to many pharmacological studies, the effect of R. communis extract on regulating adipogenesis as therapeutic drug for treating obesity has not been reported. R. communis extract (RCE) was investigated to determine its effects on the adipogenesis by monitoring the status of Wnt/β-catenin signaling and factors involving the differentiation of adipocytes. The differentiation of 3T3-L1 cells monitored by Oil Red O staining was inhibited in concentration dependent manner by RCE. The luciferase activity of HEK 293-TOP cells containing pTOPFlash with Tcf4 response element-luciferase gene was increased approximately 2-folds by the treatment of RCE at concentrations of 100 μg/mL compared to the control. Activation of the Wnt/β-catenin pathway by RCE was further confirmed by immunocytochemical analysis which shows an increment of nuclear localization of β-catenin. In addition, safety of RCE was verified through performing neural stem cell morphology assay. Among the identified flavonoids in RCE, isoquercitrin was the most abundant. Therefore, these results indicate that the adipocyte differentiation was significantly reduced by isoquercitrin in R. communis. In this study, RCE suppresses the adipogenesis of 3T3-L1 cells via the activation of Wnt/β-catenin signaling.