Advances in Internet of Things (IoT) technology drive demand for affordable, compact, lightweight, and flexible wearable devices. Flexible devices integrate functional materials (e.g., nanoparticles, nanowires, carbon nanotubes, conduc-tive polymers) with flexible substrates (e.g., fiber fabrics, polymers), combin-ing substrate flexibility with material properties like conductivity, photother-mal response, and strength. Encompassing electronic (e.g., flexible displays, circuits) and non-electronic types (e.g., paper-based chips, actuators), they find applications in energy storage, biomimetics, biomedicine, and beyond. This review covers the constituent materials, functional material patterning meth-ods, and biomedical applications of flexible devices, focusing on sens-ing/monitoring, disease treatment/healthcare, and artificial organs.