Long non-coding RNAs (lncRNAs) are important regulatory factors in tumor development and progression. The lncRNA CASC9.5 is located on chromosome 8 and has a total length of 1316 bp. CASC9.5 plays a tumor-promoting role in the development and progression of brain tumor and colon cancer; however, limited research has been conducted on the role of this lncRNA in lung adenocarcinoma. The present study analyzed 44 lung adenocarcinoma specimens and 2 lung cancer cell lines. It was found that CASC9.5 expression levels were significantly higher in lung cancer tissues and cells compared with normal lung tissues. In addition, the expression level of CASC9.5 was closely related to the TNM (tumor, node and metastasis) stage of lung adenocarcinomas, tumor size, tumor metastasis and tumor metabolism. Moreover, results of the in vivo and in vitro experiments all demonstrated that CASC9.5 promoted lung adenocarcinoma cell proliferation and metabolism by regulating the expression levels of cyclin D1, E-cadherin, N-cadherin and β-catenin. In summary, the present study demonstrated that high levels of CASC9.5 expression promote the proliferation, metastasis and metabolism of lung adenocarcinoma cells and might serve as a prognostic indicator. The present study provides novel findings regarding the diagnosis and treatment of lung adenocarcinoma.