TRIB3 roles in tumor progression have been revealed with similar or opposite results. Here, we found that TRIB3 expression was highly expressed in lung cancer tissues and correlated with tumor grades and metastasis. Functional experiments showed that TRIB3 knockdown (KD) inhibited lung cancer cell migration, invasion, EMT (epithelial-mesenchymal transition) process and stemness. Mechanistic studies demonstrated that TRIB3 physically interacted with β-catenin and increased the recruitment of β-catenin to the promoter region of genes regulated by Wnt. Re-activation of β-catenin attenuated the inhibition of TRIB3 KD on lung cancer progression. These results suggest that TRIB3 interacts with β-catenin and thus activates β-catenin signaling, which is responsible for lung cancer progression, and blocking TRIB3 activity might be developed to treat lung cancer.