AbstractThe rapid developments of the Internet of Things (IoT) and portable electronic devices have created a growing demand for flexible electrochemical energy storage (EES) devices. Nevertheless, these flexible devices suffer from poor flexibility, low energy density, and poor dynamic stability of power output during deformation, limiting their practical applications. Carbon nanofibers (CNFs) with high conductivity, good flexibility, and large‐scale preparation are regarded as promising electrodes for flexible EES devices. Based on the issues of current flexible EES devices, this review presents various strategies from the design of CNFs‐based electrodes to the fabrication of devices and overviews their applications in various flexible metal ion/air batteries (Li/Na/K‐ion batteries, Li‐S batteries, metal–air batteries, and other novel secondary batteries) and supercapacitors. Finally, the remaining challenges and perspectives on the CNFs‐based flexible EES devices are proposed to provide guidance for the researchers concentrating on high‐performance flexible EES devices.