Uncovering the patterns and underlying drivers of soil organic carbon (SOC) accumulation in response to restoration of degraded desert grasslands of Northern China can provide a scientific evidence for the effective management of degraded grasslands and the elucidation of soil carbon sequestration effects through grassland restoration. This investigation focused on the response of SOC to different stages of grassland restoration across the Ordos Plateau, which included areas of shifting sands, pre-restoration, mid-restoration, and post-restoration, at soil depths of 0-10 cm, 10-20 cm, and 20-40 cm. To unravel the factors influencing SOC, a suite of statistical techniques was employed. The results indicated that: (1) Grassland restoration significantly increased SOC across all studied depths (P ＜ 0.05). Notably, SOC increased by 8.28 times, 6.44 times, and 9.46 times at 0-10 cm, 10-20 cm, and 20-40 cm soil depths, respectively. (2) The accumulation of SOC at different depths was found to be influenced by various factors. Vegetation coverage and plant diversity were identified as the primary drivers of SOC accumulation at the 0-10 cm depth, while nutrient limitation, specifically soil nitrogen, played a significant role in the accumulation of SOC in deeper layers (10-20 cm and 20-40 cm), and this effect intensified with increasing soil depth. These findings offer a scientific foundation for informed restoration strategies of the degraded grasslands and furnish evidence for the promotion of soil carbon cycling through grassland restoration, contributing to the achievement of dual carbon goals.