Introduction: Early identification of pediatric patients at risk of clinical deterioration in the emergency department (ED) is vital for improving outcomes and optimizing survival. Pediatric Early Warning Scores (PEWS) are clinical assessment tools designed to detect such deterioration and guide care escalation decisions. Objectives: To determine the diagnostic accuracy and optimal cut-off point of the Brighton PEWS in detecting clinical deterioration events (CDE) among pediatric patients at a major emergency department in Davao City , Philippines. Methods: This retrospective cohort study included 345 pediatric patients aged 1 month to 18 years at the Southern Philippines Medical Center ED from 2021 to 2022. Physiological parameters, including heart rate, respiratory rate, and oxygen saturation, were extracted to compute Brighton PEWS values upon arrival. The primary outcome was CDE occurrence, evaluated using the Area Under the Curve (AUC) and Youden index to identify the optimal cut-off. Results: Among participants, 56 experienced CDE. Patients with CDE had significantly higher median Brighton PEWS (6.00 vs. 2.00; p