<p>The pilot initiatives of Broadband China and innovative cities are crucial strategies aimed at achieving dual carbon objectives and fostering sustainable, high-quality urban growth. A systematic assessment of their synergistic effects on urban carbon productivity is essential for effectively implementing policy combinations and promoting pilot policies. This study analyzes data from 272 cities between 2006 and 2020, using a multi-period difference-in-differences (DID) model to empirically test the impact of concurrent pilot policies on carbon productivity. The findings indicate that the dual-pilot policies significantly enhance urban carbon productivity, demonstrating a more pronounced effect than single-pilot policies. Achieving Broadband China city status before becoming an innovative city yields more favorable outcomes than the reverse order. Pathways through which dual-pilot policies enhance carbon productivity include green technological innovation, talent agglomeration, and industrial structural transformation. Heterogeneity analysis reveals that the construction of dual-pilot cities has a more significant positive impact on carbon productivity in central cities, as well as in non-resource-based cities. Collectively, these results provide valuable references for advancing the effective implementation of policies and promoting green, low-carbon urban development.</p>