Aldehyde dehydrogenase 1A1 (ALDH1A1) is an NADP-dependent enzyme belonging to the ALDH family, playing a crucial role in various physiological and toxicological processes. It is widely recognized as a marker for tumor-initiating cells and is involved in maintaining the stemness of tumor cells, promoting tumor angiogenesis and metastasis, and contributing to resistance against anticancer drugs. ALDH1A1 also lowers intracellular pH in breast cancer cells, suppressing antitumor immunity and fostering cancer progression. Recent studies have shown that ALDH1A1 upregulates ZBTB7B, a transcription factor that promotes glycolysis in tumor cells, leading to increased lactate production and immune evasion. This highlights ALDH1A1's potential as a therapeutic target for cancer immunotherapy.