With the advent of the “Information Era”, the development of an integrated infrastructure, which involves the integration of traditional transportation infrastructure and informatization development, has become a new impetus for economic growth. Meanwhile, its environmental performance remains uncovered. Using data from 30 Chinese provinces between 2013 and 2020, this study designed an index system and constructed the coupling coordination degree model to assess the development level of integrated infrastructure. The regression model was established to examine the nonlinear effect of the integrated infrastructure on carbon emissions. The influencing mechanism was also discussed through identifying the impacts of integrated infrastructure on the energy intensity, industrial structure, and technological innovation. The evaluation of the evolutionary trend showed that the level of integrated infrastructure continues to improve and displays a feature of “higher highs, lower lows”, although the regional disparity was significant. The regression analysis showed that there was an inverted U–shaped relationship between integrated infrastructure and CO₂ emissions. It is also found that most provinces were below the turning point. In the mechanism analysis section, we can demonstrate that integrated infrastructure can enhance energy intensity, which might hamper reductions in emissions. However, an integrated infrastructure facilitates the development of tertiary industry, which can lead to lower carbon emissions. Based on the conclusions, some insightful policy implications are provided.

In the pursuit of carbon neutrality goals, local governments usually face the dilemma of whether to focus on economic development or environmental protection. Regional integration is a beneficial policy solution to address the challenges inherent to this dilemma. This research considers the expansion of the Urban Economic Coordination Committee in the Yangtze River Delta as a quasi-natural experiment in regional integration. It employs the difference-in-differences model to assess its potential for fostering a win–win situation in terms of economic growth and environmental protection, with the results showing that regional integration has a significantly positive impact on attaining this win–win situation. Inhibiting pollution transfer and promoting green transformation are crucial mechanisms by which regional integration can help strike a balance between economic growth and environmental protection. However, the effects of both regional integration and win–win mechanisms are heterogeneous across cities. The conclusion suggests that the government should accelerate the implementation of regional integration policies across a wider range, recognize and maximize the important role of intermediate mechanisms, and encourage cities to adopt different strategies according to their heterogeneous characteristics, forming a high-level collaborative development pattern.