This study aimed to investigate the relationship between blood urea nitrogen to albumin ratio (BAR) and the prognosis of heart failure (HF).A total of 2125 patients with HF were included in this single-center prospective cohort study between February 2012 and December 2017. Using a receiver operating characteristic curve, we determined the cutoff value of BAR as 0.24. All patients were divided into two groups according to the cutoff value of BAR.Among 2125 HF patients, the mean age was 56.7 ± 14.3. During a median follow-up time of 22 months, 516 end-point events occurred. Compared with patients in the low BAR group, those in the high BAR group were older; more likely to be male; had a higher percentage of hypertension, diabetes, smoking, and β-blocker use; and higher levels of alanine aminotransferase, glycosylated hemoglobin, creatinine, log-transformed NTproBNP, and Blood urea nitrogen but lower levels of albumin, triglycerides, high-density lipoprotein, ApoA1, and hemoglobin. Prognosis analysis indicated that high BAR was associated with increased mortality risk of HF (Hazard Ratio = 1.497, 95% CI = 1.234-1.816; P < 0.001) in the multivariate Cox proportional hazard regression model. Subgroup analysis revealed that stratification by age, gender, history of hypertension, diabetes, smoking, β-blocker use, and levels of hemoglobin, glycosylated hemoglobin, and creatinine have no obvious effect on the association between BAR ratio and the prognosis of HF. Furthermore, patients with high BAR represented a decreased left ventricular ejection fraction and increased left ventricular end-diastolic diameter.High BAR was an independent predictor for the mortality risk of HF.