In the present study, we found that ZBTB20, a member of the POK (POZ and Krüppel) family of transcriptional repressors, was significantly up-regulated in lung cancer tissues, compared with adjacent normal tissues. Our in vitro studies further found that ZBTB20 overexpression promoted, while its inhibition using small interfering RNA suppressed cell proliferation. Consistently, key regulators in cell-cycle progression, such as Cyclin D1, Cyclin E, P21 and P27, were also regulated by ZBTB20. At the molecular level, we further revealed that FoxO1, a tumor suppressor in multiple human cancers, was transcriptionally repressed by ZBTB20. Therefore, our results highlight an important role for ZBTB20 in controlling NSCLC development, which might be helpful to identify potential therapeutic targets for its treatment.