Cancer therapy-related cardiac dysfunction (CTRCD) is an emerging disease. As there is no specific treatment for CTRCD, the standard therapy for cardiac failure is typically administered. In patients with heart failure and severe secondary mitral regurgitation, transcatheter edge-to-edge repair (TEER) of the mitral valve reduces hospitalization for heart failure and all-cause mortality. However, the effectiveness of TEER in the treatment of patients with CTRCD remains unclear. A 47-year-old woman with severe heart failure was admitted to our hospital. She had a history of a modified radical mastectomy for breast cancer and anti-human epidermal growth factor receptor-2 agents were administered after anthracycline administration. Echocardiographic assessment revealed severe cardiac dysfunction, with a reduction in the left ventricular ejection fraction (LVEF) from 60% to 20%. Cardiac magnetic resonance imaging revealed high native T1 and extracellular volume values, normal T2 values, and mild late gadolinium enhancement involving the left ventricle. An endomyocardial biopsy revealed moderate interstitial and perivascular fibrosis. Electron microscopy revealed degeneration of myofibrils, proliferation of mitochondria, and the presence of autophagosomes causing vacuolation of cardiomyocytes. Due to hemodynamic disturbances, continuous dobutamine infusion therapy was initiated and cardioprotective medication was commenced and titrated. Because low cardiac function (LVEF, 26%) and severe mitral regurgitation persisted, TEER of the mitral valve was performed, resulting in a dramatic improvement in her hemodynamic status. Twelve months post-TEER, cardiac function (LVEF 61%) recovered. We report a valuable case of CTRCD in which TEER was effective for reverse remodeling by comparing imaging and pathological evaluations.