<p>Land degradation severely undermines ecosystems’ capacity to function as carbon sinks, thereby accelerating atmospheric CO₂ accumulation and climate change. Despite a growing body of research on land restoration, the specific soil-based mechanisms driving long-term carbon sequestration across restoration strategies have not been synthesized systematically. We conducted a comprehensive systematic review of global literature from 2000 to 2024, uncovering how key soil variables mediate carbon dynamics in restored ecosystems. This review synthesizes recent advances in understanding how restoration interventions regulate soil–carbon interactions across different ecosystems. Restoration practices via afforestation, grazing exclusion, land-use conversion, terracing, wetland rehabilitation, and peatland rewetting modify key soil properties, including bulk density, soil aggregation, texture distribution, pH, and microbial community composition. These changes influence soil organic carbon (SOC) dynamics by increasing organic matter inputs from vegetation, improving soil structural stability, enhancing organo-mineral associations, and regulating microbial processing of organic carbon. In particular, the formation of stable aggregates and mineral-associated organic carbon plays a crucial role in long-term SOC stabilization. The magnitude and direction of SOC responses depend strongly on the ecosystem context, restoration age, soil mineralogy, and hydrological conditions. While restoration generally enhances SOC accumulation, trade-offs such as soil acidification or water availability constraints may influence long-term carbon sequestration outcomes. By integrating restoration pathways with soil physicochemical and biological mechanisms, this review highlights the central role of soil processes in determining the effectiveness of ecosystem restoration for climate mitigation and sustainable land management.</p>