Background: Life-threatening arrhythmias, such as ventricular and supraventricular tachycardia, are rare but serious complications of increased intracranial pressure (ICP) in children. These arrhythmias are thought to result from brainstem-mediated autonomic dysfunction.Case Report: We describe five pediatric patients (aged 7 months to 11 years) who developed malignant arrhythmias—Premature ventricular contractions, ventricular tachycardia, or supraventricular tachycardia in the context of elevated ICP due to various neurological conditions, including Arnold-Chiari malformation, autoimmune encephalitis, and acute necrotizing encephalopathy. All patients demonstrated elevated ICP (opening pressure, 32–80 mmHg), abnormal neuroimaging or transcranial doppler/optic nerve sheath diameter findings, and autonomic instability. Arrhythmias occurred during ICP surgery and required antiarrhythmic therapy in four cases. Three children recovered fully, whereas two succumbed to refractory ICP and brainstem failure. Conclusion This series emphasizes that life-threatening arrhythmias may reflect uncontrolled ICP and brainstem compromise. Early recognition, continuous neuromonitoring, and aggressive ICP-directed therapy are critical for achieving favorable outcomes.