A self-powered intracardiac pacemaker (SICP) was developed for treating arrhythmia in large animal models. The device, based on triboelectric nanogenerators, harvests biomechanical energy from cardiac motion to power the pacemaker without batteries. The SICP, with a weight of 1.75 g and volume of 1.52 cc, is delivered via a catheter into the right ventricle of swine through an intravenous route. It integrates an energy harvesting unit (EHU) and power management unit (PMU) to convert cardiac motion energy into electricity, maintaining endocardial pacing function during a three-week follow-up. The device generates an open-circuit voltage of about 6.0 V and a short-circuit current of 0.2 μA in vivo. The SICP demonstrates excellent biocompatibility, lightweight design, and stable energy harvesting performance. It effectively regulates heart rhythm and shows no significant complications in swine models. The device's energy harvesting efficiency is enhanced by its capsule structure and triboelectric nanogenerator technology. The SICP can recharge its PMU using the EHU, and it maintains stable performance even under varying tilt angles. The device is compatible with MRI and shows no significant inflammation in the endocardium. Long-term experiments confirmed the device's ability to maintain normal pacing function and prevent complications. The SICP provides a promising solution for self-powered implantable bioelectronic devices, overcoming the energy limitations of conventional pacemakers. This work demonstrates the feasibility of a minimally invasive, self-powered pacemaker for long-term cardiac pacing.A self-powered intracardiac pacemaker (SICP) was developed for treating arrhythmia in large animal models. The device, based on triboelectric nanogenerators, harvests biomechanical energy from cardiac motion to power the pacemaker without batteries. The SICP, with a weight of 1.75 g and volume of 1.52 cc, is delivered via a catheter into the right ventricle of swine through an intravenous route. It integrates an energy harvesting unit (EHU) and power management unit (PMU) to convert cardiac motion energy into electricity, maintaining endocardial pacing function during a three-week follow-up. The device generates an open-circuit voltage of about 6.0 V and a short-circuit current of 0.2 μA in vivo. The SICP demonstrates excellent biocompatibility, lightweight design, and stable energy harvesting performance. It effectively regulates heart rhythm and shows no significant complications in swine models. The device's energy harvesting efficiency is enhanced by its capsule structure and triboelectric nanogenerator technology. The SICP can recharge its PMU using the EHU, and it maintains stable performance even under varying tilt angles. The device is compatible with MRI and shows no significant inflammation in the endocardium. Long-term experiments confirmed the device's ability to maintain normal pacing function and prevent complications. The SICP provides a promising solution for self-powered implantable bioelectronic devices, overcoming the energy limitations of conventional pacemakers. This work demonstrates the feasibility of a minimally invasive, self-powered pacemaker for long-term cardiac pacing.