Renewable energy sources have attracted considerable attention in both academia and industry owing to concerns about environmental pollution, global warming, and fossil fuel depletion. In this regard, the application scope of Li-ion batteries (LIBs) is continuously broadening owing to their advantages, such as their high energy and power densities, eco-friendliness, and portability. As highly capacitive anode materials for LIBs, Si-based materials should circumvent the critical limitations of large volume expansion and low electrical conductivity. Herein, we propose hierarchically reduced SiOx as an anode material for LIBs. Using the magnesiothermic reduction process, we optimized the electrical conductivity and kinetic properties of SiOx materials based on SiO2. The resultant SiOx electrode exhibited a high specific capacity of 1,286.8 mAh g−1 along with stable cyclability up to 100 cycles. The enhanced electrochemical performance was mainly attributed to the oxygen vacancies and mesoporous surface morphology of SiOx, which were generated during hierarchical magnesiothermic reduction. This study demonstrates the correlation between the structural properties and electrochemical performance according to the reduction level of Si-based active materials.