Metastasis is a major cause leading to mortality for lung cancer patients. We identified YWHAZ as a potential metastasis-promoting candidate and found that overexpression of YWHAZ promotes lung cancer cell proliferation, anchorage-independent growth, migration, and invasion in vitro, as well as tumorigenesis and metastasis in vivo. It not only increases cell protrusions and branchings but also induces epithelial-mesenchymal transition. Most importantly, YWHAZ protein could prevent ]-catenin from ubiquitination via its association with ]-catenin and enhance slug transcriptional activity which is regulated by ]-catenin/TCF signaling pathway. Moreover, YWHAZ expression was higher in tumors than in adjacent normal tissues in 63 Non-small-cell lung cancer (NSCLC) patients. NSCLC patients with high YWHAZ expressing tumors had shorter overall survival than those with low-expressing tumors. We conclude that YWHAZ play a critical role in promoting NSCLC metastasis.