<p>Against the backdrop of China’s carbon neutrality goals, limited attention has been paid to the coordination between household carbon offset capacity and new urbanization in city clusters. This gap is especially evident when viewed through the lens of carbon source–sink synergy. This study addresses this gap by analyzing the Liaozhongnan Urban Agglomeration (LUA) from 2008 to 2022, constructing a comprehensive new urbanization indicator system encompassing population, economy, space, society, and ecology dimensions and a carbon offset capacity model to quantify their coupling coordination. Spatial autocorrelation and interaction effects were examined using Moran’s I and the Spatial Durbin Model (SDM), selected for its ability to capture both direct and spillover effects. Results show that although carbon offset capacity declined over the study period, most cities achieved favorable coupling coordination with urbanization, albeit with marked spatial disparities. Significant positive spatial autocorrelation and agglomeration effects were detected, with urbanization exerting a dominant role in enhancing offset capacity. The findings highlight the need to promote balanced development pathways, strengthen regional carbon sequestration potential, and integrate ecological planning into urbanization strategies.</p>