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Constructing dual‐ion energy storage devices using anion‐intercalation graphite cathodes offers the unique opportunity to simultaneously achieve high energy density and output power density. However, a critical challenge remains in the lack of proper anodes that match with graphite cathodes, particularly in sustainable electrolyte systems using abundant potassium. Here, a surface grafting approach utilizing multifunctional azobenzene sulfonic acid is reported, which transforms V2C MXene into a high‐kinetics K+‐intercalation anode (denoted ASA‐V2C) for dual‐ion energy storage devices. Importantly, the grafted azobenzene sulfonic acid offers extra K+‐storage centers and fast K+‐hopping sites, while concurrently acting as a buffer between V2C layers to mitigate the structural distortion during K+ intercalation/de‐intercalation. These functionalities enable the V2C electrode with significantly enhanced specific capacity (173.9 mAh g−1 vs 121.5 mAh g−1 at 0.05 A g−1), rate capability (43.1% vs 12.0% at 20 A g−1), and cycling stability (80.3% vs 45.2% after 900 cycles at 0.05 A g−1). When coupled with an anion‐intercalation graphite cathode, the ASA‐V2C anode demonstrates its potential in a dual‐ion energy storage device. Notably, the device depicts a maximum energy density of 175 Wh kg−1 and a supercapacitor‐comparable power density of 6.5 kW kg−1, outperforming recently reported Li+‐, Na+‐, and K+‐based dual‐ion devices. [ABSTRACT FROM AUTHOR]