Current guidelines do not inform about use of therapeutic hypothermia among heart failure (HF) patients who suffer from cardiac arrest. We assessed the risk of mortality associated with hypothermia among cardiac arrest survivors with HF. This analysis includes 1,416 comatose patients with cardiac arrest who achieved return of spontaneous circulation on admission and had a left ventricular ejection fraction (LVEF) assessment or HF admission within the previous year. HF was defined as either previous episode of HF or presence of left ventricular ejection fraction <50%. Hazard ratios (HR) and 95% confidence intervals (CI) for association of hypothermia and mortality among patients with and without HF were computed using Cox proportional hazard models adjusted for several risk factors. A propensity score matched analysis was also performed. There were 624 patients (44%) with pre-existing HF and 467 patients (33.0%) received hypothermia. The mortality rate was higher in HF patients treated with hypothermia compared with patients without hypothermia (75.4% vs 53.2%, p <0.0001). Hypothermia was associated with increased mortality among HF patients (HR 1.69; 95% CI 1.27, 2.24, p <0.001) and was not associated with mortality among non-HF patients (HR 1.21; 95% CI 0.93, 1.56, p = 0.15). The association of hypothermia with mortality was higher among HF patients who presented with shockable rhythm compared with nonshockable rhythm (interaction p value = 0.0495). Hypothermia is associated with increased mortality among cardiac arrest survivors with known HF.