Background <p>Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer-related deaths worldwide, marked by its aggressive nature and high likelihood of metastasis. The precise function of ret finger protein-like 3 (RFPL3) in NSCLC progression remains incompletely understood.</p> Methods <p>This study measured RFPL3 expression in NSCLC by immunohistochemistry, qPCR, and Western blot. RFPL3’s effects on proliferation were assessed with CCK-8 and colony formation assays. Transwell and wound-healing assays evaluated its role in invasion, metastasis, and EMT. In vitro and in vivo studies determined RFPL3’s mechanisms driving EMT and lymphatic metastasis.</p> Results <p>RFPL3 was overexpressed in NSCLC tissues, correlating with lymphatic metastasis and poor prognosis, establishing it as a distinct prognostic risk factor. Knockdown reduced NSCLC cell proliferation, invasion, and metastasis, while overexpression enhanced these malignant phenotypes. RFPL3 increased EMT-related protein expression by western blot, promoting tumor cell metastasis. In vivo, RFPL3 overexpression accelerated tumor growth and lymphatic metastasis in mice.</p> Conclusion <p>This study revealed the critical role of RFPL3 in NSCLC, suggesting that RFPL3 might serve as both a biomarker and a therapeutic target for this type of cancer, which provides new insight for improving patient prognoses.</p>