Nuclear ubiquitous casein and cyclin-dependent kinases substrate (NUCKS) overexpression has been reported in various types of cancers. The purpose of this study is to clarify the role of NUCKS, underlying the involvement of non-small-cell lung cancer, in the progression of lung cancer. The small interfering ribonucleic acid (siRNA) of NUCKS was transfected into a lung cancer cell line (NCI-H460, A549, NCI-H1299 and NCI-H1975). Functional experiments (MTT assay, Annexin V-FITC/PI double staining assay, colony formation assay, wound healing assay and Transwell assay) were performed to measure the effects of NUCKS on lung cancer cell viability, migration, invasion and apoptosis. NUCKS was found to be up-regulated in lung cancer cells. Knockdown of NUCKS significantly altered lung cancer cell apoptosis, proliferation colony formation, invasion and migration. Moreover, knockdown of NUCKS attenuated the activation of the PI3K/AKT pathway in lung cancer cells. NUCKS was overexpressed in lung cancer cells and played an important role in lung cancer by increasing cell growth through the PI3K/AKT signalling pathway. This in vitro study suggested NUCKS should be evaluated in a clinical setting as a novel biomarker and potential therapeutic target for lung cancer.