Polyacrylonitrile-based commercial carbon fibers (CFs) have garnered significant attention in mechanical applications because of their exceptional mechanical properties. However, their functional versatility relies heavily on the structural intricacies of duplex carbon layers. Current modification approaches, though effective, are encumbered by complexity and cost, limiting widespread adoption across diverse fields. We herein present a straightforward modification strategy centered on regulating carbon layers to unlock the multifunctional potential of CFs. Our method leverages two common anions, Cl− and SO42−, to facilitate oxidation reactions in CFs under robust alkali and high voltage conditions. Cl− effectively activates carbon layers, while SO42− facilitates layer movement. The electrocatalytic activities of the resultant CFs are enhanced, with state-of-the-art performance as supercapacitors and exceptional stability. Moreover, our approach achieves a groundbreaking milestone by bending and fusing CFs without using binders. This breakthrough can reduce the manufacturing costs of CF-based products. It also facilitates the development of novel microelectronic devices.