[Objective] Spatial network characteristics and driving forces of net carbon sequestration in the Yangtze River economic belt (YREB) were analyzed to provide a scientific reference for promoting coordinated carbon emission reduction, supporting the achievement of “dual carbon” goals and regional coordinated development. [Methods] A spatial association network of carbon sinks in the YREB was constructed at the municipal level using a modified gravity model. Social network analysis was then applied to examine the network’s characteristics and driving factors. [Results] ① From 2001 to 2021, total carbon emissions in the YREB exhibited an increasing trend, with a spatial distribution pattern of higher and lower emissions in the east and west, respectively. Conversely, total carbon sinks followed a fluctuating upward trend, showing a pattern of higher sinks in the west and lower in the east. Net carbon sinks have continuously declined, with a similar west-east gradient. ② The carbon sink network in the YREB showed significant spatial correlation, forming a complex dense in the east and sparse in the west network pattern, with Chongqing and Shanghai City emerging as dual-core nodes. The regional network exhibited high centrality, with cities such as Shanghai and Chongqing City playing key roles. The network’s overall structure demonstrated low stability. ③ Cities were categorized into four groups based on their roles within the network: net exporters, bidirectional exchanges, brokers, and net beneficiaries. Interblock spillover effects were more pronounced than intra-block associations. ④ The primary driving forces behind the spatial association network of carbon sinks were economic development, industrial structure upgrades, energy consumption intensity, and land-use patterns. [Conclusion] In the future, it is essential to consider the spatial network dynamics of net carbon sinks across cities, leveraging complementary strengths to maximize emission reduction benefits.