Fiber is a symbol of human civilization, being ubiquitous but obscure in society over most of history. Fiber has been revived upon the advent of fiberâbased electronic devices in the past two decades. This is due to its desirable lightweight, flexible, and conformable characteristics, which enable it to play a fundamental role in the electronic and information era. Numerous fiberâbased electronic devices have sprung up in energy conversion, energy storage, sensing, actuation, etc. A possibility is thereby conceived that they can be integrated into smart systems compatible with the human body, consisting of biotic fiberâbased organs and tissues, which possess similar but more advanced functions. However, the design of monoâ/multifibers, the construction of fiberâbased devices, and the integration of these smart systems represent great challenges in fundamental understanding and practical implementation. A systematic review of the current state of the art with respect to the design and fabrication of electronic fiber materials, construction of fiberâbased devices, and integration of smart systems is presented. In addition, limitations of current fiberâbased devices and perspectives are explored toward potential and promising smart integration.