Background: Pediatric intensive care units (PICUs), where children with critical illnesses are treated, require considerable manpower and technological infrastructure in order to keep children alive and free from sequelae. Methods: In this retrospective comparative cohort study, hospital records of patients aged 1 month to 18 years who died in the study PICU between January 2015 and December 2019 were reviewed. Results: A total of 2,781 critically ill children were admitted to the PICU. The mean±standard deviation age of 254 nonsurvivors was 64.34±69.48 months. The mean PICU length of stay was 17 days (range, 1–205 days), with 40 children dying early (<1 day of PICU admission). The majority of nonsurvivors (83.9%) had comorbid illnesses. Children with early mortality were more likely to have neurological findings (62.5%), hypotension (82.5%), oliguria (47.5%), acidosis (92.5%), coagulopathy (30.0%), and cardiac arrest (45.0%) and less likely to have terminal illnesses (52.5%) and chronic illnesses (75.6%). Children who died early had a higher mean age (81.8 months) and Pediatric Risk of Mortality (PRISM) III score (37). In children who died early, the first three signs during ICU admission were hypoglycemia in 68.5%, neurological symptoms in 43.5%, and acidosis in 78.3%. Sixty-seven patients needed continuous renal replacement therapy, 51 required extracorporeal membrane oxygenation support, and 10 underwent extracorporeal cardiopulmonary resuscitation. Conclusions: We found that rates of neurological findings, hypotension, oliguria, acidosis, coagulation disorder, and cardiac arrest and PRISM III scores were higher in children who died early compared to those who died later.