High-entropy spinel oxides are promising anode materials for lithium-ion batteries owing to their unique crystal structures, which provide enhanced structural stability, multiple redox-active sites, and three-dimensional Li⁺ diffusion pathways. However, the intrinsic complexity and compositional diversity of high-entropy systems have limited a comprehensive understanding of the correlation between crystal structure, elemental composition, and rate performance, thereby impeding further optimization and practical application. In this study, a high-entropy spinel oxide (Fe_0.2Co_0.2Ni_0.2Cr_0.2Zn_0.2)₃O₄ (FCNCZO) is synthesized to investigate its electrochemical properties. The material delivers a high reversible capacity of 551 mAh g⁻¹ at 500 mA g⁻¹ after 110 cycles and maintains an excellent rate capability of 330 mAh g⁻¹ at a high current density of 2000 mA g⁻¹. Density functional theory calculations indicate that the synergistic interaction among multiple metal elements reduces the bandgap and broadens the d-band width. Moreover, the high-entropy effect promotes metal-oxygen orbital hybridization, facilitates charge redistribution, and significantly enhances rate capability. These findings provide new microscopic insights into the high-entropy effect and demonstrate its potential in designing next-generation high-entropy anode materials with superior rate performance for high-power lithium-ion batteries.