Background: The blood urea nitrogen (BUN) to albumin ratio (BAR) has emerged as a potential prognostic marker in various pathological states. Aim: This study aims to elucidate the utility of BAR in predicting the incidence of acute kidney injury (AKI) and severe acute pancreatitis (SAP) in patients diagnosed with acute pancreatitis (AP). Methods: This retrospective analysis included 210 patients diagnosed with AP and monitored at a tertiary university hospital. Patients were classified into three categories based on the severity of pancreatitis: mild AP, moderately severe AP, and severe AP. Results: BAR levels increased significantly with the progression of disease severity (P < 0.001). Median BAR values were 3.3 for mild AP, 3.9 for moderately severe AP, and 11.6 for severe AP. In multivariate regression analysis, BAR was identified as an independent prognostic factor for both severe AP (odds ratio [OR] =1.341, 95% confidence interval [CI]: 1.016-1.612, P = 0.002) and AKI (OR = 1.382, 95% CI: 1.138-1.679, P = 0.001). Receiver operating characteristic (ROC) analysis indicated that a BAR threshold exceeding 5.192 predicted severe AP with a sensitivity (Sn) of 71.4% and specificity (Sp) of 82.5% (area under the curve [AUC] =0.849, P < 0.001). Additionally, a BAR threshold greater than 4.505 was found to predict AKI with a Sn of 63.2% and Sp of 86.6% (AUC = 0.782, P < 0.001). Conclusion: BAR, assessed at hospital admission, demonstrates considerable promise as a readily accessible biomarker for predicting the severity of AP and the development of AKI.