We report the nanofiber-reinforced composite electrodes as the highly transparent (~90%) and extremely foldable electrodes with lower sheet resistance (~24 Ω sq.−1) and mechanically robust (~59.7 MPa), and demonstrate the successful fabrication of flexible and transparent symmetric solid-state supercapacitors using the nanofiber-reinforced composite electrodes decorated with NiO nanoparticles in order to demonstrate the real performance. The NiO-decorated nanofiber-reinforced composite electrodes are used as both negative and positive electrodes to build the flexible and transparent symmetric solid-state supercapacitor devices. The structural, morphological, and its electrochemical properties of the fabricated flexible and transparent symmetric supercapacitors will be discussed.