RNA‐binding motif protein 5 (RBM5) acts as a tumor suppressor in various human cancers and presents with several important characteristics, such as the potentiation of apoptosis, inhibition of the cell cycle, and alternative splicing of Fas and caspase‐2 precursor mRNA. However, its role in bladder urothelial carcinoma (BUC) remains unknown. In this study, we found that RBM5 expression was significantly down‐regulated in BUC tissues when compared with the adjacent nontumor tissues. The down‐regulation of RBM5 activates ²‐catenin, which binds to the T‐cell factor/lymphocyte enhancer factor element of the miR‐432‐5p promoter and elevates the expression of miR‐432‐5p in bladder cancer cells. The up‐regulated miR‐432‐5p directly targets 3′‐UTR and depresses RBM5 expression. Thus, RBM5–miR‐432‐5p–²‐catenin forms a feedback loop in regulating bladder cancer cell apoptosis. Our findings provide evidence that the regulatory feedback loop among RBM5, miR‐432‐5p, and Wnt–²‐catenin is responsible for the progress of bladder cancer cells.—Zhang, Y.‐P., Liu, K.‐L., Wang, Y.‐X., Yang, Z., Han, Z.‐W., Lu, B.‐S., Qi, J.‐C, Yin, Y.‐W., Teng, Z.‐H., Chang, X.‐L., Li, J.‐D., Xin, H., Li, W. Down‐regulated RBM5 inhibits bladder cancer cell apoptosis by initiating an miR‐432‐5p/²‐catenin feedback loop. FASEB J. 33, 10973–10985 (2019). http://www.fasebj.org