Purpose Soil organic carbon (SOC) is integral to the global carbon cycle. However, the distribution and governing factors of SOC in karst regions remain poorly understood due to frequent land use changes and regional microclimate heterogeneity. Methods This study was conducted at long-term pilot monitoring stations that had been in place for 13-17 years. A survey transect was established extending from the southwest to the northeast of Guizhou Province, China, to statistically assess variations in soil organic carbon storage (SOCs) across five land use categories (i.e., sloping farmland, bare land, grassland, orchard, and arbor woodland). Results We found that the SOCs was substantially greater in orchards and arbor woodlands than in grasslands and sloping farmlands. Sloping farmland and grassland SOCs were influenced mainly by annual precipitation (MAP) and altitude (AL), whereas total soil phosphorus (TP) was the main influence on bare land (P < 0.05), orchard (P < 0.05) and arbor woodland (P < 0.01) SOCs. Structural equation modeling revealed that land use (path coefficient: 0.16, P < 0.01) and soil chemical properties (path coefficient: 0.39, P < 0.01) directly governed SOCs, whereas climate (path coefficient: 0.31, P < 0.01) indirectly influenced SOCs by mediating land use. Furthermore, the impact of soil chemical properties on SOCs was limited by land use and soil particle type. Variable decomposition analysis revealed that soil chemical properties independently explained 31.00% of the variation in SOCs, whereas climate, land use, soil chemical properties and soil particle composition together explained 27.08% of the variation in SOCs. Conclusion Our results provide valuable insights for the development of targeted strategies to increase SOC sequestration in karst areas, emphasizing the need to consider local microclimate factors, soil qualities, and land use types when managing carbon. [GRAPHICS]