Cirrhosis is a healing response to persistent liver injury, and the widely used clinical indicators of cirrhosis severity are limited. The lactate/albumin ratio (LAR) can be used as a marker of early prognosis in critically ill patients. The aim of this study was to explore the clinical significance of LAR for predicting the prognosis of patients with cirrhosis and to provide new insights. Patients diagnosed with liver cirrhosis were extracted from the MIMIC- IV database. The cox regression models were used to analyze the association between the LAR and all-cause mortality in cirrhosis patients. We analyzed potential nonlinear relationships between LAR and outcome indicators using restricted cubic spline cures (RCS). The predictive power was investigated using receiver operating characteristic(ROC) analysis. Additionally, we calculated the incremental effect of the LAR index. The study included a total of 2402 patients with cirrhosis. According to the Kaplan-Meier curves and cox regression analysis indicated that the risk of 28-day, 90-day, 180-day, 1-year all-cause mortality was significantly higher in the highest quartile of LAR. The result of the multivariable RCS model showed the LAR index have a linear relationship (p for nonlinear = 0.115) with 28d all-cause mortality. The area under the ROC curve (AUC) of LAR (66.44% [95% CI 0.64-68.88%]) was superior to lactate (63.51% [95% CI 61.01-66.01%]) and albumin (64.46% [95% CI 62.01-66.92%]). The predictive ability of scoring tools for 28d mortality was significantly improved after considering either the LAR index using integrated discrimination improvement index (IDI). The LAR index can serve as a significant predictor for all-cause mortality in critically ill patients with liver cirrhosis.