Acute Kidney Injury (AKI) is a clinical syndrome characterized by an abrupt decrease in kidney function resulting in accumulation of waste products and critical fluid and electrolyte imbalances. KDIGO (Kidney Disease: Improving Global Outcomes) provides two sets of criteria to identify and classify acute kidney injury (AKI): serum creatinine (SCr) and urine output (UO). Objectives: To assess the performance of the SCr and UO criteria for identification of AKI in the PICU and compare the standard SCr criteria to consistent, and easily measurable urine output parameter. Materials and Methods: This is a prospective observational study that was conducted in the PICU of Department of Pediatrics, Dayanand Medical College and Hospital, Ludhiana. All patients between 1 month and 18 years admitted to PICU of a tertiary care center with >24 hours of stay were screened for AKI using the KDIGO classification with SCr and UO criteria. Results: The study included 446 patients admitted to the PICU, out of which 116 (26%) developed AKI, classified into Group A: 97 cases (83.6%), diagnosed by both S. Cr and/or UO; Group B: 19 cases (16.3%) (UO only with normal serum creatinine); and C:330 cases (no AKI). Mean difference between time to detect AKI between UO and serum creatinine criteria was 8.46 hours, suggesting UO detected AKI approximately 8 hours earlier on average. Conclusion: The study highlights the superior sensitivity of urine output as an early indicator of kidney dysfunction. This reinforces the KDIGO recommendation of using both parameters synergistically for diagnosis of AKI.