Abstract Aims Impaired renal function (IRF) prevails in patients with acute heart failure. The study aimed to investigate the prevalence of on‐admission IRF and its association with short‐term and long‐term mortalities in patients hospitalized for HF with reduced (HFrEF), mildly reduced (HFmrEF), and preserved (HFpEF) left ventricular ejection fraction (LVEF). Methods Patients hospitalized for acute heart failure were enrolled and stratified by LVEF into three phenotypes as HFpEF (≥50%), HFmrEF (40–49%), and HFrEF (