The use of natural biological waste materials as precursors to prepare biochar substrate for flexible energy storage filed possess natural richness, sustainable and environmental friendliness, compared with carbon materials derived from fossil raw materials. Herein, we prepare carbonized silk fabric (CSF) based on natural silk waste fabric as a flexible substrate, which qualifies a 3D conductive network and good mechanical flexibility. The as-prepared ZnCo2O4-loaded carbonized silk fabric (ZCO/CSF) acts as anode for lithium-ion battery, exhibiting high reversible capacity and superior rate capacity. In addition, due to CSF's unique fabric weave structure, the ZCO/CSF shows excellent foldable flexibility and deformation recovery properties. The flexible full cell containing ZCO/CSF as anode can power a light-emitting diode (LED) both when folded twice and rolled. Thus, our work opens the door to the development of biomass-based flexible substrates in flexible energy storage devices.