Two-dimensional transition metal carbides/nitrides (MXenes) have become a hotpot for energy storage, which possess desirable surface chemistry property and conductivity. However, MXenes presents a lower capacity and deteriorative cycle performance due to surface passivation and Van der Waals’ force. Herein, the self-oxidized PA@Ti3C2Tx materials are developed via the functionalization with phytic acid. The derived anatase TiO2 structure endows the material with stubborn lithium-ion migration pathway and satisfactory electrochemical reversibility. The self-sacrifice of outer Ti layers is confirmed by the evolution of lattice fringes extending from the inside to the outside, and the break of Ti-C bond provides the sites for the combination with phosphorus. The rapid charge transfer and reduced energy barrier induced by Ti-O-P bond also enhances the lithium-ion diffusion kinetics. The 1/2PA@Ti3C2Tx material shows promoted rate performance of 180.2 mAh g–1 at 3000 mA g–1. The assembled lithium-ion capacitor also acquires a superior energy density of 344.3 Wh kg–1 at the power density of 73.7 W kg–1, and maintains the energy density of 65.7 Wh kg–1 at the power density of 6836.3 W kg–1. This strategy of structure regulation via self-oxidation can effectively improve the high-power performance of MXenes in lithium-ion capacitors.