Updated project metadata. Ca2+ overload-induced mitochondrial dysfunction is considered as a major contributing factor in the pathogenesis of alcohol-associated liver disease (ALD). However, the initiating factors that drive mitochondrial Ca2+ accumulation in ALD remain elusive. Here, we demonstrate that an aberrant increase in mitochondria-associated ER membranes (MAMs) mediates Ca2+ accumulation-induced mitochondrial dysfunction in ALD via the formation of glucose-regulated protein 75 (GRP75)-mediated MAM Ca2+-channeling (MCC) complex. Unbiased transcriptomic analysis reveals pyruvate dehydrogenase kinase 4 (PDK4) as a prominently inducible MAM kinase in ALD. Additional mass spectrometry analysis unveils the critical role of PDK4 in promoting alcohol-induced MCC complex formation and mitochondrial dysfunction by phosphorylating GRP75. Non-phosphorylatable GRP75 mutation or genetic ablation of PDK4 prevents alcohol-induced mitochondrial Ca2+ accumulation and dysfunction. Conversely, ectopic induction of MAM formation in PDK4-deficient mice abrogate the protective effect in alcohol-induced liver injury. Together, our study defines the mediatory role of PDK4 in promoting mitochondrial dysfunction in ALD.