Myocardial ischemia-reperfusion (MIR) injury is a major cause of adverse outcomes of revascularization after myocardial infarction. To identify the fundamental regulator of reperfusion injury, we performed metabolomics profiling in plasma of individuals before and after revascularization and identified a marked accumulation of arachidonate 12-lipoxygenase (ALOX12)-dependent 12-HETE following revascularization. The potent induction of 12-HETE proceeded by reperfusion was conserved in post-MIR in mice, pigs, and monkeys. While genetic inhibition of Alox12 protected mouse hearts from reperfusion injury and remodeling, Alox12 overexpression exacerbated MIR injury. Remarkably, pharmacological inhibition of ALOX12 significantly reduced cardiac injury in mice, pigs, and monkeys. Unexpectedly, ALOX12 promotes cardiomyocyte injury beyond its enzymatic activity and production of 12-HETE but also by its suppression of AMPK activity via a direct interaction with its upstream kinase TAK1. Taken together, our study demonstrates that ALOX12 is a novel AMPK upstream regulator in the post-MIR heart and that it represents a conserved therapeutic target for the treatment of myocardial reperfusion injury.