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Straw incorporation is crucial to soil organic carbon (SOC) sequestration, thus improving soil fertility and mitigating climate change. The fate of straw C and the associated net SOC balance remain largely unexplored, particularly in soils subjected to long-term mineral and organic fertilization. To address this, soil (delta C-13:-19 parts per thousand) that had been continuously cropped with maize for 31 years and subjected to five long-term fertilization regimes, including (i) control (Unfertilized), (ii) mineral fertilizer (NPK) application, (iii) 200% NPK (2 x NPK) application, (iv) manure (M) application, and (v) NPK plus manure (NPKM) application, was incubated with or without addition of rice straw (delta C-13:-29 parts per thousand) for 70 days. Straw addition largely primed SOC mineralization. The priming effect (PE) was considerably higher in 2 x NPK ( +122% of CO2 from soil without straw addition) but lower in M (+43%) relative to the unfertilized soil (+ 82%), highlighting the importance of fertilization in controlling PE intensity. Fertilization increased the straw-derived microbial biomass C by 90-577% and straw-derived SOC by 34-68% compared to the unfertilized soil, primarily due to the increased abundance of Gram-negative bacteria and cellobiohydrolase activity. Straw-derived SOC was strongly positively correlated with straw-derived microbial biomass C, suggesting that dead microbial biomass (necromass) was a dominant precursor of SOC formation. Consequently, fertilization facilitated microbial utilization of straw C and its retention in soil, particularly in the M and NPKM fertilized soils. The amounts of straw-derived SOC overcompensated for the SOC losses by mineralization, resulting in net C sequestration which was highest in the NPK fertilized soil. Our study emphasizes that NPK fertilization decreases the intensity of the PE induced by straw addition and increases straw C incorporation into SOC, thus facilitating C sequestration in agricultural soils.