Background: Acute Kidney Injury (AKI) is a common and severe complication among children in Pediatric Intensive Care Units (PICUs), associated with high morbidity and mortality. This study evaluates the incidence, risk factors, electrolyte imbalance, and outcomes of AKI using RIFLE and AKIN criteria. Methods: A prospective observational study was conducted at a tertiary care center in Rajasthan, enrolling children aged 1 month to 14 years. Demographic, clinical, and laboratory data were collected, with AKI staged using both RIFLE and AKIN criteria. PRISM III scores were calculated. Results: Of 221 children admitted to the PICU, 57 (25.7%) developed AKI. The 2–5year age group was most affected. Leading causes included sepsis (21%), dehydration (14%), and hypovolemia (12%). Electrolyte abnormalities, particularly metabolic acidosis and hyperkalemia, were common. Mortality among AKI patients was 28%. Significant predictors included sepsis, cardiac disease, younger age, and higher PRISM scores. Conclusion: AKI significantly increases risk of mortality and hospital stay in critically ill pediatric patients. Early recognition and management of sepsis, cardiac dysfunction, and fluid-electrolyte imbalances are critical.