Exploring the desired anode materials to address the issues of poor structural stability tardy redox kinetics caused by large potassium ionic radius are fatal for the realization of large-scale applications of potassium-ion batteries. In this work, the feasibility to achieve promoted K⁺ storage by constructing the model of CoS₂ enfolded in carbon was verified by the density functional theory calculations. And the results predicted a faster electron/potassium ion transport kinetics than bare CoS₂ by increasing electron carrier density and narrowing diffusion barrier. Therefore, an interfacial engineering strategy was applied and implemented to synthesize the CoS₂ nanoparticles enveloped in the S-doped carbon (CoS₂/SC) under this inspiration. The as-prepared CoS₂/SC composite exhibited a prominent rate capability and long cycling lifespan, delivering the high capacity of 375 mA h g⁻¹ at 0.2 A g⁻¹ at the 100th cycle and 273 mA h g⁻¹ at 2 A g⁻¹ over 300 cycles. The in/ex situ characterizations unraveled the converse mechanism of CoS₂/SC in K⁺ storage, showing an eventually reversible phase transformation of ${\mathrm{K}}_{\mathrm{x}}{\mathrm{C}\mathrm{o}\mathrm{S}}_2\leftrightarrow \mathrm{C}\mathrm{o}$ within the electrochemical reactions.