Fiber-shaped supercapacitors (FSCs) are a promising candidate as power source or energy storage unit in wearable/stretchable electronics. However, it is still a significant challenge to design FSCs with excellent electrochemical performance while maintaining good flexibility to meet the requirement of wearable/stretchable electronics. Here, a human hair-based flexible all-solid-state asymmetric FSCs has been rationally designed and successfully prepared. Importantly, the as-obtained FSCs show extraordinary flexibility and outstanding electrochemical performance with a wide potential window, excellent rate capability (up to 20,000 mV·s^-1), fast frequency response (τ₀=55 ms), high volumetric energy density, and long cycle stability. The strategy presented here not only provides a reference for the construction of high-performance flexible FSCs, but also paves a new way to explore the next-generation portable/wearable energy storage devices.