Cytochrome P450 2E1 (CYP2E1) is a cytochrome P450 enzyme that catalyzes the metabolism of toxic substrates. CYP2E1 is upregulated in heart disease, including the dilated cardiomyopathy (DCM) mouse model. Here, knockdown of CYP2E1 significantly ameliorated the dilated left ventricle, thin wall, and dysfunctional contraction in the cTnT(R141W) and adriamycin-induced DCM mouse models. Interstitial fibrosis, poorly organized myofibrils, and swollen mitochondria with loss of cristae were improved in the myocardium of α-myosin heavy chain (MHC)-cTnT(R141W)×CYP2E1-silence double-transgenic mice when compared with the cTnT(R141W) transgenic mice. Oxidative stress, the activation of caspase 3 and caspase 9, the release of cytochrome c, and the apoptosis in the myocardium were significantly decreased in double-transgenic mice compared with the cTnT(R141W) transgenic mice. In summary, the expression of CYP2E1 is upregulated in heart disease and might be induced by hypoxemia in cardiomyopathy. The overexpression of CYP2E1 can enhance the metabolism of endogenous ketones to meet the energy demand of the heart in certain disease states, but the overexpression of CYP2E1 can also increase oxidative stress and apoptosis in the DCM heart. Knockdown or downregulation of CYP2E1 might be a therapeutic strategy to control the development of DCM after mutations of cTnT(R141W) or other factors, because DCM is the third most common cause of heart failure and the most frequent cause of heart transplantation.