Cardiac tamponade (CT) is a rare but potentially lethal complication associated with central venous catheters (CVCs). We present a 6-year-old boy who developed CT after CVC insertion in the right internal jugular vein, with its tip in the inferior vena cava. Initially, he was hospitalized to a tertiary hospital with presumptive diagnoses of pneumonia and left ankle cellulitis. Three days after CVC placement, he developed CT, manifesting as recurrent episodes of hypotension and bradycardia. Once a bedside echocardiography showed CT, pericardiocentesis was performed, resulting in successful resuscitation. Pericardiocentesis revealed a milk-appearing pericardial fluid, indicating chylopericardium. The boy also underwent debridement and joint irrigation of the left ankle, which turned out to be osteomyelitis. Although CVC tips in most reported CVC-related CTs have been commonly located in the right atrium, our case featured a tip located in the inferior vena cava. Additionally, chylopericardium was likely due to the extravasation of total parenteral nutrition fluid, rather than the usual causes, such as recent thoracic surgery. Understanding the mechanisms behind chylopericardium associated with CVCs and timely pericardiocentesis is crucial for improving the outcomes.