This article reports the case of a female with late infantile neuronal ceroid lipofuscinosis who developed right and left anterior bundle branch blocks and episodic bradycardia at 23 years of age. Several episodes of supraventricular tachycardia manifested at 23 and 27 years of age. In addition, a transient second‐degree atrioventricular conduction block also emerged at 27 years of age. Atrial fibrillation and aggravation of the atrioventricular conduction block resulted in progressive bradycardia and cardiac death at the age of 28 years. Cardiac involvement and accumulation of lipopigments in the myocardium and cardiac conduction system have been recognized in juvenile neuronal ceroid lipofuscinosis, but this is the first report to describe progressive conduction defects in a case of late infantile neuronal ceroid lipofuscinosis.