Flexible electronic devices are regarded as one of the key technologies in wearable healthcare systems, wireless communications and smart personal electronics. For the realization of these applications, wearable energy and sensor devices are the two main technologies that need to be developed into lightweight, miniaturized, and flexible forms. In this review, we introduce recent advances in the controlled design of device structures into bioinspired micro/nanostructures and 2D/3D structures for the enhancement of energy harvesting and multifunctional sensing properties of flexible electronic skins. In addition, we highlight their potential applications in flexible/wearable electronics, sensors, robotics and prosthetics, and biomedical devices.