Under the guidance of the “dual carbon” goal, carbon sinks, as important regulatory ecological products provided by ecosystems, have made significant contributions to promoting the internalization of carbon emission externalities and mitigating climate change. Its compensation mechanism is increasingly becoming a key lever for promoting regional collaborative governance. However, the horizontal compensation mechanism for carbon sink supply and demand remains in the exploratory stage, both in theoretical construction and practical application. Focusing on the Beijing-Tianjin-Hebei (BTH) region, this study constructs three carbon sink supply-demand ratio scenarios of 10%, 20%, and 30%, based on the theories of public goods and development rights. The coefficient method is employed to calculate the total supply and demand of carbon sinks in the BTH region in 2023, and the market value method is utilized to assess their economic value. Furthermore, a “natural-economic-social” multi-factor compensation accounting model is constructed by incorporating the “carbon sink compensation priority sequence” and “carbon sink compensation demand intensity”, which reflect regional differences in natural endowments. It also includes the “emission intensity” and “migration degree”, which reflect interregional linkages. Finally, two compensation models are designed: “traditional cross-regional horizontal carbon sink supply and demand compensation” and “bottom-up cross-regional carbon sink supply and demand compensation”. The compensation results are then compared and analyzed with the financial pressure of various cities/regions in the BTH region. The results indicate that: (1) There is a significant spatial mismatch between carbon emissions and carbon sinks in different cities/districts of the BTH region, especially in the southwestern and northern regions. (2) Under three different scenarios of carbon sink supply and demand ratios, the total compensation amount for the BTH region in 2023 is 1659, 1554, and 1480 million yuan, respectively. The main compensation areas are Chengde City and Zhangjiakou City in Hebei Province, as well as Huairou District and Miyun District in Beijing. The main payment areas are Langfang City, Tangshan City, and Cangzhou City in Hebei Province. (3) The “bottom-up” compensation mechanism, implemented in the scenario with a 10% carbon sink supply-demand ratio, achieves an optimal balance between fiscal affordability and regional coordination. This study proposes a two-stage regional compensation path of “balancing at the district level first and then coordinating across cities”, which can improve the adaptability and implementation flexibility of the system while ensuring the coordinated promotion of regional emission reduction responsibilities and ecological protection. This provides an innovative paradigm for promoting multi-level and differentiated carbon sink compensation mechanisms in other urban agglomerations nationwide.