Land use/cover change (LUCC) plays a key role in regulating the carbon cycle. Carbon storage (CS) is shaped by natural conditions, vegetation status, land use type, and socioeconomic activities. However, their effects on CS in Xinjiang, an arid region of northwest China, remain inadequately understood. Clarifying the spatiotemporal dynamics of LUCC and CS is essential for climate change mitigation, carbon neutrality, and sustainable development. This study integrated the InVEST and PLUS models to assess historical and future CS changes in Xinjiang. Random forest (RF) and geographically weighted regression (GWR) were applied to identify the drivers of CS spatial heterogeneity. The results show that (1) CS exhibits a clear spatial pattern, with higher values in mountainous areas and lower values in unused land. From 2000 to 2020, total CS increased by 87.5 million t. (2) Natural factors, especially slope and normalized difference vegetation index, were the dominant drivers of CS spatial heterogeneity, while socioeconomic factors, including gross domestic product and population density, also had significant effects. (3) Total carbon storage increases to varying degrees under all five scenarios. The Ecological Conservation Scenario (ECS), total carbon storage increases by 7.36 & times; 107 t; the Natural Development Scenario (NDS), it increases by 12.13 & times; 107 t; the Rapid Development Scenario (RDS), it increases by 1.47 & times; 107 t; the Cropland Protection Scenario (CPS), it increases by 10.97 & times; 107 t; and the Sustainable Development Scenario (SDS), it increases by 2.90 & times; 107 t. Based on these findings, we propose policies to safeguard and enhance CS, including stronger ecological protection, limits on urban and cropland expansion, and a balance between conservation and development to support China's carbon neutrality. Overall, this study clarifies CS dynamics and drivers in Xinjiang, informing management in arid regions.