Lignin which is the second most abundant renewable source is found to be the most promising candidate for environmentally benign energy storage materials because of its high carbon content, biodegradability, favorable functionality and economic feasibility. Therefore, the design of lignin into a renewable energy storage material is anticipated to offer an innovative sustainable chemistry and extension the application fields of wood biomass. Here, we have used electrospinning method for preparing lignin incorporated PAN nanofiber as porous electrode material and have synthesized lignin based hydrogel electrolyte by crosslinking it with chemical crosslinker. Ultimately we have fabricated all-solid-state flexible supercapacitor exhibiting a maximum energy density and power density of 4.49 Wh kg^-1 and 2.63 kW kg^-1, respectively by integrating the lignin-PAN nanofiber electrode and lignin hydrogel electrolyte.