<p>Under the new development paradigm, the digital economy has emerged as a crucial driver of China’s green development. Utilizing a quasi-natural experiment of the “Broadband China” strategy, this paper examines its impact on carbon productivity through a multi-period difference-in-differences model, a moderating effect model, and a spatial panel model. The findings indicate that the policy significantly enhances carbon productivity. As population size increases, the policy impact initially flattens, then rises, and eventually decreases before flattening again. The effect is particularly pronounced in the eastern and central regions, the southern region, and the first batch of demonstration cities. Furthermore, innovation, financial development, and urbanization amplify the policy’s effectiveness in boosting carbon productivity. From a spatial perspective, the digital economy positively influences carbon productivity of both local and neighboring areas. This research provides insights for further advancing Digital China and accelerating “dual carbon” goals.</p>