Sudden death in children and young adults, while uncommon, carries profound clinical and societal implications. Cardiac causes, particularly inherited arrhythmias and cardiomyopathies, account for most cases, though neurologic, toxicologic, traumatic, and infectious etiologies also contribute significantly. This review explores the epidemiology, classification, and pathophysiologic mechanisms of sudden death in this population, emphasizing early clinical warning signs and identifiable risk factors. We also outline diagnostic and preventive strategies, including electrocardiography, genetic testing, and postmortem evaluation. Despite guidelines advocating preparticipation screening, real-world implementation remains inconsistent. Advances in genomics and artificial intelligence offer new opportunities for early risk detection. Finally, we discuss public health interventions such as defibrillator access, cardiopulmonary resuscitation education, and school-based protocols as essential components of a broader prevention strategy.