As the most common type of lung cancer, lung adenocarcinoma (LUAD) poses a great threat to human health worldwide and severely compromises the quality of life of the patients. The present study aimed to explore the potential pathogenesis of LUAD. Reverse transcription-quantitative PCR and western blotting were applied to measure the expression levels of SEC61 translocon subunit γ (SEC61G) and cyclic AMP-responsive element-binding protein 3 (CREB3). Western blotting was also used to determine the expression of endoplasmic reticulum (ER) stress-, apoptosis- and migration-related proteins. Cell Counting Kit-8, colony formation, TUNEL, wound healing and Transwell assays were used, respectively, to determine the viability, proliferation, apoptosis, migration and invasion of LUAD A549 cells. The association between SEC61G and CREB3 was verified by co-immunoprecipitation assay. The results revealed that SEC61G was upregulated in A549 cells and its downregulation could activate ER stress. It was also found that silencing SEC61G inhibited the malignant development of LUAD through ER stress. In addition, SEC61G was verified to participate in ER stress in LUAD via CREB3 and silencing SEC61G exerted inhibitory effects on the malignant progression of LUAD by regulating CREB3. In summary, SEC61G participated in ER stress and its knockdown exerted inhibitory effects on A549 cells via regulating CREB3, which suggests that SEC61G may be a potential therapy for patients with LUAD.