Carbon derived from plants and microbial is important in the development of soil organic carbon (SOC); however, the role of the degradation and accumulation processes of such carbon in ecosystem restoration is poorly explored. Therefore, we investigated grassland (GL), Prunus sibirica (PRS), Caragana korshinskii (CAK), and Robinia pseudoacacia (ROP) as vegetation restoration types, with farmland (FL) as the control. Soil physical and chemical properties, residue carbon, microbial metabolic activities, enzyme activities, and carbohydrate-active enzyme (CAZyme) genes were quantified across these five vegetation types in the Loess Plateau, China. Vegetation restoration significantly enhanced the contents of SOC, plant residue carbon (PRC), microbial necromass carbon (MNC), bacterial necromass carbon (BNC) and fungal necromass carbon (FNC). MNC was the dominant in FL, GL, PRS, and CAK, whereas PRC predominated in ROP. BNC contributed more in FL, while FNC had a stronger role in restored vegetation types. Our results demonstrated significant shifts in CAZyme gene abundance across vegetation types, with gene abundance negatively correlated with soil pH and positively correlated with microbial biomass carbon and respiration. Increased abundance of CAZyme genes for cellulose, lignin, and peptidoglycan degradation correlated positively with PRC and FNC. By linking residue carbon pools to microbial functional genes, this study provides mechanistic insights into SOC regulation during vegetation restoration. These microscale processes have significant implications for scaling SOC sequestration potential to regional and global levels, informing ecosystem management strategies for climate change mitigation.