A 25-year-old man presented to the emergency department with acute-onset chest pain and shortness of breath. A physical examination revealed coarse crackles in the both lower lungs. Consolidation and ground-glass opacities suggesting viral infection were detected in the right lower lobe on chest computed tomography. Laboratory findings revealed elevated troponin, leukocytosis, and lymphopenia. Electrocardiography revealed ST segment elevation with PR depression in leads I, aVL, V5, and V6, and ST depression and PR elevation in aVR. Echocardiography revealed diffuse cardiac hypokinesia and a decreased left ventricular ejection fraction. Suspecting coronavirus disease 2019 (COVID-19)-related myopericarditis, the patient was hospitalized. After one week of empirical antibiotics, antivirals, and supportive therapy, his condition improved. Antibody testing for COVID-19 was positive on hospitalization day 8. The presentation of myopericarditis can be vague and mislead physicians during the COVID-19 pandemic. Myopericarditis should be included as a differential diagnosis for patients with suspected COVID-19.