SF has been demonstrated to possess many superior properties, including remarkable biocompatibility, adjustable biodegradability, and water solubility, excellent optical transmittance, good mechanical robustness, light weight and ease of processing, which render it extremely suitable for the construction of next-generation biocompatible flexible electronic devices. Some preparation technologies, such as electrospinning, 3D printing, spin coating, soft lithography, freeze drying, particulate leaching, and ultrasonic induction, have been introduced to process SF materials in diverse forms, i.e., silk fibers, silk films, silk sponges, and silk hydrogels, for various application areas. Owing to the desired biological properties, SF is widely used as fundamental components, i.e., substrates and encapsulation materials as well as scaffolds, of flexible wearable and implantable electronic devices, such as electronic skins, bioabsorbable electronics, and therapy electronics. In addition, in recent years, flexible electronic devices in which SF serves as a functional material have gained more attention. First, SF was found to have piezoelectric properties and a strong ability to lose electrons; therefore, it was used as a dielectric material to build piezoelectric energy harvesters and triboelectric energy harvesters. Second, owing to the characteristics of SF sensitive to environmental variables, many flexible sensors with SF functional components have been proposed, such as humidity sensors, temperature sensors, pressure sensors, airflow sensors, and electrochemical sensors. Third, some other types of flexible electronic devices using SF as a functional material were also developed, including resistive switching memory devices, OFETs, OLEDs, filters, and actuators, which further expanded the application field of SF. Table 1 summarizes the recent SF-based applications.