Plastic biliary stents are commonly placed during endoscopic retrograde cholangiopancreatography for various indications, and stent-related complications are uncommon. We describe a case in which a plastic biliary stent migrated proximally through the liver capsule and diaphragm after endoscopic retrograde cholangiopancreatography, leading to pericardial effusion and cardiac tamponade. It is important for clinicians managing patients with biliary stents to be aware of this significant adverse event.