Acute kidney injury (AKI) is a common complication among children experiencing critical illness, and is associated with both short- and long-term morbidity and mortality. In this review, we discuss current evidence for AKI in paediatric critical care including definitions, epidemiology, pathophysiology, risk factors, and strategies for diagnosis, management, and prognosis. Around one in four children admitted to paediatric intensive care units (ICUs) experience AKI, with higher rates among at-risk groups including children with sepsis, malignancy, post-stem cell transplantation, neonates, cardiac and liver disease, and amongst children exposed to nephrotoxic medications. Critically ill children are at risk due to systemic inflammation, microvascular flow alternations, endothelial dysfunction and microthrombi in the context of serious illness. Management is primarily supportive, with up to 5% of critically ill children requiring renal replacement therapy, most often due to pathologic fluid accumulation. Future research priorities include integration of novel biomarkers into routine care for early detection and risk stratification, with a potential role for artificial intelligence. Large-scale, multi-centre prospective studies, including low- and middle-income settings, are needed to improve understanding of risk factors and outcomes for this vulnerable group.