The irreversible loss of cardiomyocytes due to oxidative stress is the main cause of heart dysfunction following ischemia/reperfusion (I/R) injury and ageing-induced cardiomyopathy. Here, we report that CUEDC2, a CUE domain-containing protein, plays a critical role in oxidative stress-induced cardiac injury.Cuedc2−/− cardiomyocytes exhibited a greater resistance to oxidative stress-induced cell death. Loss of CUEDC2 enhanced the antioxidant capacity of cardiomyocytes, promoted reactive oxygen species (ROS) scavenging, and subsequently inhibited the redox-dependent activation of signaling pathways. Notably, CUEDC2 promoted E3 ubiquitin ligases tripartite motif-containing 33 (TRIM33)-mediated the antioxidant enzyme, glutathione peroxidase 1 (GPX1) ubiquitination, and proteasome-dependent degradation. Ablation of CUEDC2 upregulated the protein level of GPX1 in the heart significantly. Strikingly,in vivo, the infarct size ofCuedc2−/− heart was significantly decreased after I/R injury, and agedCuedc2−/− mice preserved better heart function as the overall ROS levels in their hearts were significantly lower. Our results demonstrated a novel role of CUEDC2 in cardiomyocyte death regulation. Manipulating CUEDC2 level might be an attractive therapeutic strategy for promoting cardiomyocyte survival following oxidative stress-induced cardiac injury.