Aims <p>The role of microbial necromass in aggregate mediated soil C sequestration under cropland management remains poorly constrained, limiting prediction and management of SOC. This study aimed to quantify effects of cropland management on aggregate associated microbial necromass and identify key drivers.</p> Methods <p>A global-scale meta-analysis combined with weighted random forest analysis was employed.</p> Results <p>Cropland management practices extensively promoted microbial necromass accumulation within aggregates. Cover crops significantly decreased fungal necromass carbon (FNC)/bacterial necromass carbon (BNC) by 27.67% (<i>n</i> = 16) in small microaggregates (&lt; 53&#xa0;μm), but notably increased it by 41.50% (<i>n</i> = 28) in microaggregates (53–250&#xa0;μm). Manure did not alter FNC/BNC. NPK fertilization significantly decreased FNC/BNC by 8.79% (<i>n</i> = 37) in large macroaggregates (&gt; 2000&#xa0;μm). No/reduced tillage (NT/RT) increased FNC/BNC by 37.30% (<i>n</i> = 38) in microaggregates (53–250&#xa0;μm). Straw application significantly decreased FNC/BNC by 8.98% (<i>n</i> = 96). Cover crops and manure increased FNC contribution to SOC in small microaggregates and microaggregates, wheras NPK addition increased BNC contribution to SOC in microaggregates and small macroaggregates (250–2000&#xa0;μm). These effects are mainly driven by a shift in dominant controls as aggregate size decreases, from substrate supply (SOC, C/N) to physicochemical conditions (pH, texture). Moreover, management effects on fungal necromass were primarily linked to SOC and C/N, whereas those on bacterial necromass were mainly constrained by pH and texture.</p> Conclusion <p>Our results provide a basis for soil-specific management strategies to enhance stable soil C sequestration by regulating necromass formation and distribution within aggregates, such as prioritizing cover crops in sandy soils to increase fungal necromass in macroaggregates.</p>