Overexpression of frequently rearranged in advanced T-cell lymphomas 1 (Frat1) has been reported in several human malignant tumors, but the relationship between Frat1 and β-catenin in lung cancer is still unclear. Our goal was to investigate the correlation between Frat1 and β-catenin in patients with lung cancers. Immunohistochemistry was performed in 110 cases of non-small cell lung cancer (NSCLC) with clinical follow-up. Results showed that both Frat1 and β-catenin were overexpressed in NSCLC. The expression of Frat1 and β-catenin was significantly correlated with tumor differentiation, TNM stage, and lymph node metastasis. Interestingly, the overexpression of β-catenin was positively correlated with the overexpression of Frat1 (correlation coefficient = 0.285; P = 0.003). In addition, overexpression of Frat1 and abnormal expression of β-catenin were found to represent a poor prognosis for the patients. Furthermore, based on the transfection of Frat1 and β-catenin, we found that Frat1 can upregulate the expression of β-catenin in BE1 cells.