Abstract: Dynamic changes in the soil organic carbon (SOC) storage in farmland are closely related to fertilization strategies and climate change. To explore fertilization strategies for increasing the crop yield and sequestering carbon under climate change, this study used summer maize farmland in purple soil areas as the research object. The Denitrification-Decomposition (DNDC) model was calibrated and validated using long-term-positioning monitoring experiments, and the calibrated DNDC model was combined with future climate data from the CMIP6 model to study the effects of different fertilization measures (CK: control with no fertilization; T1: combined application of organic and chemical fertilizers; T2: chemical fertilizer application; T3: increased chemical fertilizer application) on summer maize yield and SOC storage under three future scenarios (baseline, SSP2-4.5, and SSP5-8.5 scenarios). Results show that under both SSP scenarios, the precipitation and temperature in the study area showed an upward trend over time, with the SSP5-8.5 scenario showing more pronounced upward trends in precipitation and temperature. The mean bias error (MBE) between measured and simulated maize yield and surface SOC content across treatments showed satisfactory agreement, with normalized root mean square error (NRMSE) of 0.07–0.19 and coefficient of determination (R²) of 0.74–0.98, respectively, indicating a good simulation performance and be able to simulate summer maize yield and SOC in purple soil areas of the model. Under the T1 treatment, there was no significant difference in SOC storage under various future scenarios in most eras, and climate change had a relatively small impact on the yield and SOC storage under combined application of organic and chemical fertilizers. Under CK treatment, the maize yields under SSP2-4.5 and SSP5-8.5 scenarios increased significantly compared to that under the baseline scenario; however, the maize yield under the two SSP scenarios decreased significantly treated with chemical fertilizer alone. Under the CK, T2, and T3 treatments, the SOC storage under each scenario showed a decreasing trend over time, whereas under the T1 treatment, the SOC storage under each scenario showed an increasing trend over time. By 2100, the SOC storage of each treatment showed a trend of T1 > T3 ≈ T2 > CK. Under different fertilization measures, by 2100, the SOC loss under the SSP5-8.5 scenario is higher than that under the SSP2-4.5 scenario, i.e., the high emission scenario leads to pronounced SOC loss. Research has shown that under future climate change, although conventional fertilization methods can ensure stable crop yields, they are not conducive to carbon sequestration in farmland. The combination of organic and chemical fertilizers is a more suitable fertilization management mode for achieving carbon sequestration and increased yield in purple soil farmland.