Micron-sized silicon-based materials have attracted immense attention for large-scale lithium-ion batteries (LIBs) owing to high theoretical capacity and low cost. However, it is limited by severe volume expansion and fast capacity fading in a cycling process. Here, we proposed a facile strategy to obtain an in situ formed carbon nanosheet template-covered micron-sized porous silicon composite (PSi@CNS) from the low-cost Al–Si alloy and bicontinuous C₆H₁₂O₆/SiO₂ structural layer. The templated assembly of the inner distributed PSi and outer in situ generated CNS can form a stable and controllable conductive structure with an increased specific surface area and enhanced intermolecular interactions. This unique composite structure results in a significant increase of electrolyte transfer and long-term stability. As an anode material for LIBs, the PSi@CNS composite exhibits a high reversible capacity of 1272 mA h g^–1 at 1 A g^–1 after 500 cycles in the micron-sized PSi/C composite system. This work provides a templated idea for long-term stable LIBs.