Objective: Upper gastrointestinal bleeding (UGIB) is a common condition in emergency departments (ED). The aim of this study is to evaluate the effectiveness of the red blood cell distribution width (RDW) to albumin ratio and three types of shock index (SI) as predictors of adverse outcomes in patients with UGIB in the ED. Methods: The study was designed as a retrospective, single-center study, and patients were screened using electronic medical records. Glasgow Blatchford, RDW/albumin ratio, SI, modified SI (MSI), and age SI were calculated, and adverse outcomes were defined as ICU admission, red blood cell transfusion, in-hospital mortality, and 30-day mortality. The effectiveness of these parameters in predicting adverse outcomes in UGIB patients admitted to the ED was evaluated. Results: The study enrolled 174 patients, of whom 17.2% required admission to the ICU, 33.9% received red blood cell transfusions, and 10.3% died within 30 days. Patients with adverse outcomes had significantly higher SI, MSI, age SI, and RDW/albumin ratio values. All four indices were statistically significant predictors of adverse outcomes (area under the curve [AUC] SI: 0.676; AUC MSI: 0.706; AUC age SI: 0.778; AUC RDW/albumin: 0.787). Age SI showed significantly higher prognostic performance in predicting adverse outcomes than SI and MSI. Conclusion: The present study suggests that SI, MSI, age SI, and RDW/albumin ratio may be useful in predicting adverse outcomes in patients with UGIB. The RDW/albumin ratio was effective in predicting mortality, while age SI showed a higher predictive ability for adverse outcomes compared to SI and MSI.