Biomass-derived carbon materials for lithium-ion batteries emerge as one of the most promising anodes from sustainable perspective. However, improving the reversible capacity and cycling performance remains a long-standing challenge. By combining the benefits of K₂CO₃ activation and KMnO₄ hydrothermal treatment, this work proposes a two-step activation method to load MnO₂ charge transfer onto biomass-derived carbon (KAC@MnO₂). Comprehensive analysis reveals that KAC@MnO₂ has a micro-mesoporous coexistence structure and uniform surface distribution of MnO₂, thus providing an improved electrochemical performance. Specifically, KAC@MnO₂ exhibits an initial charge-discharge capacity of 847.3/1813.2 mAh·g^–1 at 0.2 A·g^–1, which is significantly higher than that of direct pyrolysis carbon and K₂CO₃ activated carbon, respectively. Furthermore, the KAC@MnO₂ maintains a reversible capacity of 652.6 mAh·g^–1 after 100 cycles. Even at a high current density of 1.0 A·g^–1, KAC@MnO₂ still exhibits excellent long-term cycling stability and maintains a stable reversible capacity of 306.7 mAh·g^–1 after 500 cycles. Compared with reported biochar anode materials, the KAC@MnO₂ prepared in this work shows superior reversible capacity and cycling performance. Additionally, the Li⁺ insertion and de-insertion mechanisms are verified by ex situ X-ray diffraction analysis during the charge-discharge process, helping us better understand the energy storage mechanism of KAC@MnO₂.