Acute kidney injury (AKI) is a common complication in patients with decompensated cirrhosis and is also an important cause for poor outcome. This study aimed at investigating the clinical characteristics and long-term prognosis of AKI in patients with hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF). A total of 1167 patients with HBV-related ACLF from January 2010 to January 2015 were enrolled and divided into two groups, AKI group (n=308) and non-AKI group (n=859). All patients were followed up to investigate clinical characteristics, long-term overall survival (OS) and risk factors. AKI occurrence was found to be 26.4% in patients with HBV-related ACLF. The patients in the AKI group and the non-AKI group had a 30-day OS of 44.8% and 70.3%, 90-day OS of 17.9% and 55.4%, and 1-year OS of 15.6% and 51.2%, respectively. Significant differences were observed in the 30-day, 90-day and 1-year OS among subgroups with different AKI stages. It was found that high WBC, neutrophil, ALT and MELD score were risk factors for 30-day mortality, whereas hepatic encephalopathy, high MELD score, mean arterial pressure and PLT were risk factors for 90-day mortality. Two criteria, the KDIGO and AKIN, showed parallel results in staging AKI in patients with HBV-related ACLF (κ=0.807, P<.001). AKI is closely associated with increased short-term mortality in Chinese HBV-related ACLF patients, particularly in those with infection and high MELD score. Both KDIGO and AKIN criteria can be used for staging AKI in patients with HBV-related ACLF.