Traditional polysomnography (PSG) systems are limited by cumbersome hardware, inefficient clinical workflows, and significant patient discomfort, hindering accurate characterization of natural sleep. Here, we present a wearable sleep-breathing monitoring system based on a printed electronic skin (E-skin) sensor that enables comfortable, high-fidelity, and home-viable respiratory assessment. The device employs a resistive eutectic gallium-indium-tin (EGaInSn) liquid-metal sensing layer screen-printed onto a flexible thermoplastic polyurethane (TPU) substrate, offering stable sensitivity over a broad dynamic range, mechanical robustness, and seamless skin conformability for long-term wear. A six-channel sensing network was implemented to capture thoracic and abdominal respiratory dynamics across diverse sleeping positions. Comprehensive clinical validation was conducted against gold-standard PSG, with respiratory events independently scored by Registered Polysomnographic Technologists (RPSGTs) under single-blind conditions. The system demonstrates high concordance with PSG in identifying obstructive and central sleep apnea, hypopnea, Cheyne–Stokes respiration, and respiratory rate abnormalities. By integrating flexible electronics and clinically aligned signal interpretation, this work advances wearable health technologies from conventional physiological monitoring toward credible diagnostic capability, providing a practical solution for continuous, accurate evaluation of sleep-related breathing disorders.