Background and aims <p>Microbial necromass carbon (C) significantly contributes to soil organic carbon (SOC) sequestration. However, there is limited information on how biochar amendment affects the accumulation and allocation of microbial necromass C in soil aggregates in paddy soil remains scarce, particularly with regard to changes in microbial life strategies.</p> Methods <p>From a 2-year field experiment, topsoil samples with biochar (C15) and without biochar amendment (C0) treatments were collected and fractionated into macroaggregate (2000–250&#xa0;μm), microaggregate (250–53&#xa0;μm), and silt–clay (&lt; 53&#xa0;μm) fractions. We investigated the impact of maize straw-derived biochar amendment on microbial community structure, SOC, and microbial necromass C in paddy soil aggregates.</p> Results <p>Biochar amendment significantly increased SOC and microbial biomass C but reduced microbial necromass C concentration. The microbial community shifted towards K-strategists under biochar amendment. Compared with the C0 treatment, total necromass C concentration in the C15 treatment decreased by 14.9% in the bulk soil, primarily due to reductions in fungal and bacterial necromass C concentrations of 14.7% and 16.1%, respectively. The decrease in total necromass C was primarily observed in macroaggregate and microaggregate. Specially, fungal necromass C primarily decreased in macroaggregate, while bacterial necromass C decreased in microaggregate. Biochar amendment did not significantly reduce microbial necromass C in silt–clay fraction, indicating its greater stabilization due to strong binding with soil minerals under biochar amendment, thereby protects it from microbial decomposition.</p> Conclusions <p>The results offer new insights into the role of soil aggregates in microbial-mediated SOC sequestration following biochar amendment in paddy soil.</p>