Background Prognoses and long‐term cardiac function of patients with fulminant myocarditis have not been fully elucidated. Therefore, we clarified the prognoses and long‐term cardiac function according to required percutaneous mechanical circulatory support and histological findings among patients with fulminant myocarditis. Methods and Results We conducted a multicenter retrospective medical record review of 216 patients with fulminant myocarditis requiring percutaneous mechanical circulatory support. Sixty‐one patients were treated with intra‐aortic balloon pump or Impella alone, and 155 patients received veno‐arterial extracorporeal membrane oxygenation and were treated with or without intra‐aortic balloon pump or Impella. Histologically, 107 patients had lymphocytic myocarditis; 34, eosinophilic myocarditis; and 4, giant cell myocarditis. Freedom from composite end point (death, durable left ventricular assist device implantation, and heart transplantation) was 66% at 90 days, 62% at 1 year, and 57% at 6 years. Veno‐arterial extracorporeal membrane oxygenation use was associated with poor prognosis in the multivariable analysis (hazard ratio [HR], 5.27; 95% CI, 1.60–17.36). The eosinophilic myocarditis subgroup showed better prognosis (HR, 0.28; 95% CI, 0.10–0.80) compared with the lymphocytic myocarditis subgroup but not in the multivariable analysis. Ventricular tachycardia/ventricular fibrillation rhythm at admission, high C‐reactive protein level, and no endomyocardial biopsy were also associated with poor prognosis. The left ventricular ejection fraction at 1 year was ≤50% in 16% of patients and was lower in patients with eosinophilic myocarditis (median: 57.9% [48.8–65.0%]) than in those with lymphocytic myocarditis (65.0% [58.6–68.7%]) ( P =0.036). Conclusions Patients with fulminant myocarditis who received veno‐arterial extracorporeal membrane oxygenation had a poor prognosis. Long‐term cardiac function was impaired in some patients, especially those with eosinophilic myocarditis.