<p>Facing the mounting challenges of global climate change, the building industry has garnered significant attention due to its substantial contribution to carbon emissions and its immense potential for emission reduction. Achieving effective carbon reduction in this sector necessitates coordinated development across both upstream and downstream industries within the industrial chain. This study constructs an industrial synergistic development indicator system in China. Utilizing the Spatial Durbin Model, it investigates the spatial effects and mechanisms of industrial synergistic development on building carbon emission intensity. The following are the primary findings: (1) Industrial synergistic development exerts a significant negative spatial spillover effect on per capita building carbon emission intensity. (2) The improvement in the level of industrial synergistic development in neighboring regions has a stronger suppressive impact on local building carbon emission intensity compared to local advancements. (3) Building energy-saving technology serves as a pivotal intermediary, yet the moderating influence of the industrial chain linkage level attenuates its mediating influence. Based on these findings, the study offers actionable recommendations for policymakers to promote carbon reduction in the building sector.</p>