Lung adenocarcinoma (LUAD) is a subtype of lung cancer that occurs frequently and results in high mortality and morbidity, comprising almost 50% of all cases with the disease. Previously, long non-coding RNAs (lncRNAs) was evidenced to be helpful in the diagnosis and prognosis of LUAD. lncRNA AGAP11 was identified as a dysregulated lncRNA in LUAD. Whether AGAP11 is linked to the progression and prognosis of LUAD has not been known. The purpose was to probe the action of AGAP11 in the LUAD progression together with its intrinsic mechanism, with a view to supplying a perspective biomarker and therapeutic target for LUAD. AGAP11 expression in LUAD was analyzed by searching in the GEPIA database and conducting RT-qPCR. The significance of AGAP11 for the prognosis of LUAD was assessed by statistical analyses. The targeting relationship between AGAP11 and miR-494-3p was corroborated with Dual-luciferase reporter assay. The role of AGAP11 on cellular processes in LUAD cells was evaluated by CCK-8 and Transwell assays. AGAP11 was markedly down-regulated in LUAD and tightly correlated with TNM stage, lymph node metastasis, and tumor differentiation degree of patients. Down-regulation of AGAP11 was found to predict a dismal prognosis of LUAD. AGAP11 negatively modulated miR-494-3p expression by interacting with it. The growth, migration, and invasion of LUAD cells could be impaired by AGAP11 overexpression, which would be attenuated by the enhanced miR-494-3p expression. AGAP11 acted as a predictor for prognosis and curbed LUAD progression through modulating miR-494-3p.