To decarbonize the atmosphere, recarbonize the soil. Soil recarbonization can significantly mitigate climate change by enhancing carbon sequestration and reducing atmospheric CO₂ concentrations. Among all, cropland soil plays a crucial role in this case, but its long-term carbon sequestration potential under changing climatic conditions remains highly uncertain in semi-arid regions of India. This study quantified historical and future soil organic carbon (SOC) dynamics and the associated climate mitigation potential of croplands for Karvir in western India by using the RothC and InVEST models. Model validation against field-measured SOC samples from 126 locations revealed good agreement-characterized by an R2 of 0.73, RMSE of 4.41 t C ha−1, and slight underestimation bias (ME = −0.79 t C ha−1)-thereby confirming the robustness of the RothC simulations. Historical SOC showed that there was a rapid annual SOC accumulation from 2010–2024, with high sequestration rates at the cropland category at 8.08 t C ha−1 y−1. However, under Coupled Model Intercomparison Project Phase 6 (CMIP6) climate scenarios, future projections under both shared socioeconomic pathway (SSP2-4.5 and SSP5-8.5) are marked by a considerable decline in their sequestration capacity. The rates at which SOC sequestrations decline are as follows: to 0.41 t C ha−1 y−1 from 2030 to 2050, and to 0.29 t C ha−1 y−1 from 2050 to 2100 under SSP2-4.5, and to 0.31 and 0.25 t C ha−1 in case of SSP5-8.5. By 2100, the stocks of SOC continue to rise in both SSP2-4.5 and SSP5-8.5, but the rates of sequestration continue to fall, showing saturation and reduced efficiency in carbon accumulation. Although, total (TSOC) stocks continue to accumulate under all scenarios, it is evident that the sequestration rate declines significantly, suggesting lower efficiency in accumulation and saturation. Overall, the findings of this study have shown that although western Indian croplands have acted historically as effective carbon sinks, future warming, moreover, under high-emission pathways, substantially constrains their long-term SOC sequestration and climate change mitigation capacity under current agricultural conditions.