The carbonate rock weathering carbon sink is a fundamental and dynamic component of the karst carbon cycle, playing a crucial yet often overlooked role in regional carbon budgets. A deep understanding of its impact mechanisms on ecosystem services (ES) is therefore essential for achieving sustainable ecosystem management in karst regions, which are among the world's most ecologically fragile landscapes. However, prevailing research paradigms have predominantly focused on evaluating single ES in isolation. This approach has created a significant knowledge gap regarding how the carbonate rock weathering carbon sink influences the complex, long-term trade-offs and synergistic relationships between multiple pairs of ES over time. To address this critical gap, our study focuses on the extensive karst terrain of Southwest China, the largest contiguous karst area globally, as an exemplary case. By leveraging a comprehensive, long-term dataset from 2000 to 2020, which integrates multi-source remote sensing imagery and meteorological reanalysis data, we employed a coupled methodological framework. This framework combines a process-based thermodynamic dissolution model, specifically calibrated for karst environments, with advanced spatial statistics and correlation analysis. The primary objective was to quantitatively unravel the dynamic evolution of trade-offs and synergies among three critical ESs-soil conservation, water yield, and carbon storage-as they are influenced by the spatiotemporal variations in the carbonate rock weathering carbon sink flux. Our results reveal several key findings. The average carbonate rock weathering carbon sink flux in the Southwest karst region was 7.04 t C km^-2 a^-1, exhibiting a significant and persistent annual increase of 40 kg C/km². Concurrently, all three ESs showed widespread and marked improvement, with over 75% of the area displaying statistically significant positive trends for each service. The pairwise relationships between these ESs were overwhelmingly synergistic, dominating more than 69% of the study area. Notably, a simultaneous enhancement of all three services-a "win-win-win" scenario-was achieved in 52.4% of the region. A pivotal discovery was that the strength of these synergies positively correlated with the magnitude of the carbonate weathering carbon sink, intensifying as the carbon sink increased.In conclusion, our findings underscore the critical importance of integrating geological carbon sink processes into the assessment and management of ecosystem services. By explicitly accounting for the influence of carbonate rock weathering, our study provides a more mechanistic and nuanced understanding. This refined knowledge is indispensable for informing and optimizing the efficacy of regional ecological restoration projects and policy decisions, ultimately supporting the synergistic achievement of ecological sustainability and carbon neutrality goals in vulnerable karst landscapes.