Pericarditis is a rare presentation of thyrotoxicosis associated with Graves disease. This association has not been previously described in the pediatric literature. We report a 17-year-old male patient who presented with chest pain, dyspnea, and tachycardia. He was found to have diffuse ST-segment elevation consistent with pericarditis. At presentation, he was noted to have bilateral proptosis. Abnormal thyroid function studies and an elevated thyroid-stimulating hormone receptor antibody level confirmed the diagnosis of Graves thyrotoxicosis. The patient was treated with anti-inflammatory and antithyroid agents and improved in time. We discuss previously reported cases of Graves disease-associated pericarditis in adults, potential etiologies, and management strategies.