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Biological pacemakers represent a promising alternative to electronic devices for treating life-threatening bradycardia, which remains constrained by risks of infection, lead failure, and lack of autonomic responsiveness. Recent advances show that biomaterials can reprogram quiescent ventricular cardiomyocytes into pacemaker cells without reliance on viral vectors, genetic modification, or exogenous cell therapy. Here, we demonstrate a functional, device-free biological pacemaker generated by intracardiac injection of silk fibroin hydrogel in a preclinical porcine model of complete heart block with syncope. This intervention reliably restored physiological, autonomically regulated rhythms and prevented syncope for up to four weeks. Induced pacemaker cells exhibited distinct morphology and Hcn4 expression at the injection site in silk fibroin–treated animals, but not in controls. The biological pacemaker fully replaced electronic pacing, meeting clinical standards with a favorable safety profile. Furthermore, intracardiac echocardiography–guided catheter delivery enabled precise, titratable administration and minimized off-target effects. These findings establish silk fibroin hydrogel as a clinically scalable platform for device-free rhythm restoration, offering a viable alternative to electronic pacing and laying the foundation for first-in-human translation.