As China enters the critical stage of green economic and social transformation under the “double carbon” goal, the strategic significance of smart city construction in “empowering” and “accelerating” urban development has become more prominent. Based on the panel data of 221 prefecture-level cities from 2003 to 2020, this paper selects multi-period DID and PSM-DID models to empirically test the impact of smart city construction on urban carbon emissions from the perspective of industrial transformation and upgrading, and further verifies the rationality of the conclusion combined with a variety of robustness tests.

The main conclusions are as follows: First, smart city construction is an important driving force for the low-carbon development of the regional economy, with an average effect of 19.84%-22.83%. Combined with a variety of robustness tests such as replacing carbon emission indicators, excluding other policies, and counterfactual testing, the core conclusions are still highly significant. Second, industrial transformation and upgrading is an effective way for smart city construction to curb regional carbon emissions. The two-way empowerment of smart city construction and industrial green transformation and structural upgrading enabled by the new generation of digital technology is an important way for the region to overcome the dilemma of “stabilizing development and promoting emission reduction”. On the whole, it can reduce the regional carbon emission intensity by 7.35%-9.87%. Third, from the perspective of industrial transformation and upgrading, the carbon emission reduction effect of smart city construction has significant heterogeneity. Specifically, at the level of characteristic indicators, the carbon emission reduction effect of high-level green technology innovation and digital development foundation is more significant; in terms of geographical location, the carbon emission reduction effect in the eastern, central and southern regions is highly significant, while the effect in the northeastern, western and northern regions is not obvious; at the level of resource endowment, human capital, economic foundation, economic agglomeration and environmental regulation level are all important factors for smart city construction to play a role in carbon emission reduction from the perspective of industrial transformation and upgrading, and cities with low comprehensive strength have more significant carbon emission reduction potential.

In a word, the two-way empowerment of smart city construction and industrial transformation and upgrading can create a new pattern of circular economy and play an important role in carbon emission reduction and green transformation of regional economy. The conclusions help to activate the “innovation dividend” and “structural dividend” of the regional carbon emission reduction effect of smart city construction from the perspective of industrial transformation and upgrading, and also provide path support and decision-making basis for realizing the policy vision of “deep integration of emerging technologies and green low-carbon industries”.