Background The triglyceride-glucose (TyG) index is increasingly recognized for its ability to predict cardiovascular and metabolic risks. This study investigated the correlation between the TyG index and the risk of acute kidney injury(AKI) in critical ill patients with acute pancreatitis(AP). Methods The Medical Information Mart for Intensive Care IV database was retrospectively searched to identify AP patients hospitalized in the intensive care unit. The primary outcome measure was the incidence of AKI. The secondary endpoint was in-hospital mortality and the rate of renal replacement therapy(RRT) use. Cox regression analysis and restricted cubic spline were used to analyze TyG index association with AKI risk. Kaplan-Meier survival analysis was performed to assess the incidence of endpoints in the different groups. Results A total of 848 patients were enrolled. The incidence of AKI was 61.56%.The in-hospital mortality was 11.69%. Kaplan-Meier analysis showed that the TyG index >= 8.78 group has a high incidence of AKI and high risk of requiring RRT (P < 0.001). Multivariable Cox regression analysis showed whether TyG index was a continuous variable (HR, 1.65 [95% CI 1.10-2.48], P = 0.015) or a categorical variable (HR, 1.72 [95% CI 1.09-2.79], P = 0.028), and the TyG index was independently associated with the risk of AKI in AP patients. The restricted cubic splines model illustrated the linear relationship between higher TyG index and increased risk of AKI in this specific patient population. Conclusions High TyG index is an independent risk factor for AKI in critical ill patients with AP. Assessing the TyG index may be beneficial for early stratification and interventions to improve prognosis.