The association between the total bilirubin/albumin (B/A) and the all-cause mortality of critically ill patients with acute kidney injury (AKI) remains unclear. This retrospective study aimed to investigate the relationship between B/A ratio and mortality in patients with AKI. The clinical data of AKI patients in the Medical Information Mart for Intensive Care III (MIMIC-III) database were retrospectively analyzed. Patients were divided into the low and high B/A groups (B/A less than or equal to 0.25 and B/A > 0.25, respectively). The primary outcome was 28-day all-cause mortality, and the secondary outcomes were 60-day, 1-year and 4-year all-cause mortality. Kaplan-Meier survival curves and Cox proportional risk models were constructed to evaluate the effect of B/A on survival outcomes. The 28-day mortality rates were 18.00% and 25.10% in the low and high B/A groups, respectively (P < 0.001). The Kaplan-Meier analysis showed that patients with higher B/A values had higher all-cause mortality risk (log-rank P < 0.0001). The multivariate Cox proportional risk analysis showed that B/A was an independent risk predictor for death at 28 days, 60 days, 1 year, and 4 years. B/A is an independent risk factor for increased mortality in patients with AKI and may be used as a predictor of clinical outcomes in AKI.