Lung adenocarcinoma (LUAD) is the most common histological type of non-small cell lung cancer (NSCLC). Due to the nonspecific early symptoms, the majority of the diagnosed LUAD patients are in the middle and late stages, with multiple metastases, and have missed the optimal period for treatment. Current studies have reported lncRNA DARS-AS1 as a cancer-promoting gene that expedites tumorigenesis. This is the first study demonstrating that DARS-AS1 is involved in the mediating process of LUAD. Cell functional experiments revealed that lncRNA DARS-AS1 participated in enhancing LUAD proliferation, invasion, and migration by inhibiting miR-188-5p. The investigation on DARS-AS1/miR-188-5p led to the discovery of KLF12 as a downstream target of miR-188-5p, and the regulatory pathway was established as DARS-AS1/miR-188-5p/KLF12. According to western blot results, DARS-AS1 promoted LUAD cell growth, migration, and invasion via stimulation of the PI3K/AKT pathway, activating the EMT process, and up-regulating the CyclinD1 and Bcl-2 proteins. This was the first report on the DARS-AS1/miR-188-5p/KLF12 axis and offered a novel strategy for early diagnosis, a new therapeutic method, and an improved prognosis for LUAD.