BACKGROUND: Cardiac tumors in children are rare and usually have no obvious clinical symptoms. However, a small number of children may experience serious conditions such as arrhythmia, heart obstruction, and even death. When severe arrhythmia cannot be controlled by conservative treatment, surgical intervention is needed. CASE PRESENTATION: A 20-day-old male neonate, born full-term via cesarean section, was admitted to the emergency department with complaints of jaundice for 16 days and a rapid heart rate detected for one day. The heart rate was recorded at 280 beats per minute. An electrocardiogram (ECG) initially suggested supraventricular tachycardia, later progressing to ventricular tachycardia. A bedside echocardiogram indicated an intracardiac mass. Conservative treatment failed to restore normal heart rhythm, then the patient underwent emergency surgery with tumor resection under general anesthesia and cardiopulmonary bypass. Post-surgery, ventilator-assisted breathing was administered, along with inotropic support, diuretics, anti-infective therapy, and fluid management. the heart rate and rhythm returned to normal. Postoperative pathology revealed the presence of a cardiac rhabdomyoma, and follow-up was arranged post-discharge. CONCLUSION: Cardiac tumors in children are relatively rare, mostly benign, and have a good prognosis. But for some emergency situations or heart tumors that cause adverse effects, timely and effective intervention is needed to avoid adverse consequences.