Background: Lung adenocarcinoma (LUAD), the most common subtype of lung cancer, has an unfavorable prognosis. ABCA4 has been identified as an oncogene in multiple malignancies, but its specific mechanisms in LUAD remain poorly understood. This study aims to explore the function of ABCA4 in LUAD with a focus on mitophagy. Methods: ABCA4 expression in LUAD was evaluated using the TCGA database, western blotting, RT-qPCR, and immunohistochemistry. The effects of ABCA4 knockdown on LUAD progression were examined in vitro (CCK8, Muse (R) Cell Analyzer, Transwell), and in vivo through (xenogeneic tumor experiments). Mitophagy was assessed by JC-1, TMRE, and DCFH-DA staining, the Muse Oxidative Stress Kit, transmission electron microscopy, and western blotting. Chloroquine (CQ) and S7306 were applied in rescue experiment. RNA-seq identified differentially expressed genes (DEGs) after siABCA4 treatment, and the effects of ABCA4 on LUAD by modulating TMSB4X were explored. Results: ABCA4 was up-regulated in the TCGA database, LUAD tissues, and cell lines. ABCA4 knockdown inhibited proliferation and tumor growth while promoting apoptosis and mitophagy. Mechanistically, siABCA4 increased AMPK phosphorylation levels. CQ or S7306 partially reversed these biological effects. Additionally, ABCA4 may interact with TMSB4X to regulate mitophagy via the AMPK pathway, thereby influencing LUAD progression. Conclusions: ABCA4 was overexpressed in LUAD, and its knockdown might promote mitophagy in LUAD progression via the AMPK pathway by modulating TMSB4X, suggesting that ABCA4 could serve as a therapeutic target for LUAD patients.