The Hippo-Yap pathway conveys oncogenic signals, but its regulation during cancer development is not well understood. Here, we identify the nuclear receptor RARg as a regulator of the Hippo-Yap pathway in colorectal tumorigenesis and metastasis. RARg is downregulated in human colorectal cancer tissues, where its expression correlates inversely with tumor size, TNM stage, and distant metastasis. Functional studies established that silencing of RARg drove colorectal cancer cell growth, invasion, and metastatic properties both in vitro and in vivo. Mechanistically, RARg controlled Hippo-Yap signaling to inhibit colorectal cancer development, acting to promote phosphorylation and binding of Lats1 to its transcriptional coactivator Yap and thereby inactivating Yap target gene expression. In clinical specimens, RARg expression correlated with overall survival outcomes and expression of critical Hippo-Yap pathway effector molecules in colorectal cancer patients. Collectively, our results defined RARg as tumor suppressor in colorectal cancer that acts by restricting oncogenic signaling by the Hippo-Yap pathway, with potential implications for new approaches to colorectal cancer therapy.Cancer Res; 76(13); 3813-25. Ó2016 AACR.