Metastasis is responsible for the majority of deaths of cancer patients. However, mechanisms governing metastasis in colorectal cancer (CRC) remain largely unknown. Here we investigated how CRC cells acquire metastatic potential using a novel mouse model of CRC that spontaneously develops liver metastasis, generated by introducing sporadic mutations of Ctnnb1, Kras, Trp53, and Smad4 (CKPS) genes. Proteomic analyses revealed elevated expression of CRC stem cell markers ALCAM (CD166) and PROM1 (CD133) in CRC cells from the metastatic model compared with those from a non-metastatic model. Spleen-to-liver metastasis assays using CRC cells derived from the CKPS model (CKPS cells) demonstrated the functional importance of ALCAM and PROM1 in initiating metastasis. Genetic and pharmacological analyses using CKPS cells in 2D and spheroid culture revealed that expression of ALCAM and PROM1 is regulated positively and negatively by the cAMP/PKA/CREB and TGF-β/SMAD4 pathways, respectively. Consistently, phospho-CREB was expressed in both primary and metastatic lesions of CKPS mice and CRC patients, and knockout of CREB in CKPS cells reduced their spheroid-forming and metastasis-initiating abilities. Treatment with a CREB inhibitor potentiated the effect of irinotecan in suppressing liver metastasis by CKPS cells. These results reveal the essential roles of ALCAM and PROM1, as well as their upstream regulators, the cAMP/PKA/CREB and TGF-β/SMAD4 pathways, in maintaining the stemness and metastatic potential of CRC cells and indicate that CREB inhibition may be a potential therapeutic strategy against metastatic CRC.