<p>The continuous rise in greenhouse gas concentrations poses an irreversible threat to the earth system, while soil depletion and degradation are gradually eroding the basis of human survival. Therefore, the development of efficient technologies that combine carbon reduction and soil improvement is imperative. Although various carbon fixation and soil remediation methods have emerged in recent years, most of them have limitations such as single effects, complex operations, and high costs. This study proposed and validated a composite system based on biochar synergistic microbially induced carbon fixation (BC-MICF), which demonstrated dual advantages in carbon dioxide fixation and soil structure improvement. The research results indicated that after the application of the BC-MICF system, the carbon fixation potential of the soil reached 17703.8&#xa0;mg, and the carbon fixation rate increased to 83.58&#xa0;mg C•m^− 2•d^− 1, representing an 10948.90% and 9768.00% increase compared to the S group. Furthermore, the content of large-diameter soil aggregates (diameter &gt; 2&#xa0;mm) increased by 218%, soil structural stability and water stability increased by 84.07% and 48.43%, respectively, basic nutrient retention rates increased by 7.49%-10.25%, porosity increased by 68.94%, significantly improving soil water conductivity, air permeability, and enhancing its water retention, fertilizer retention, and erosion resistance capabilities. The BC-MICF system not only effectively reconstructed soil ecological functions and hydrological characteristics, but also achieved the goal of stably storing atmospheric CO₂ in the soil, thereby transforming soil from a “carbon source” to a “carbon sink”, thus providing a novel technical path and theoretical support for simultaneously addressing the dual crises of climate change and land degradation.</p>