As one of the essential components for flexible electronics, flexible electrochemical energy storage (EES) has garnered extensive interests at all levels of materials, devices, and systems. The successful implementation of high-performance flexible EES devices relies on exploring of suitable electrode/electrolyte materials that have both superior electrochemical and mechanical properties. For this function, one-dimensional electrospun nanofibers have emerged as a class of promising building blocks for the key components of flexible EES devices, including those in supercapacitors, metal-ion batteries, and metal-air batteries. Here we are trying to overcome the existing challenges and prospects of these electrospun nanofiber-based flexible EES in developing the optimal high-performance and low cost flexible EES devices for long-awaited practical applications.