Against the backdrop of the increasingly prominent issues of energy security and environmental pollution, improving the mismatch of energy factors is of vital importance for achieving the strategic goals of sustainable development. In recent years, the development model of smart cities, which emerges from the integration of information technology and urban governance, has been regarded as an important way to optimize the regional allocation of resources. However, there is a lack of sufficient attention on whether it can solve the problem of energy mismatch. Based on the urban panel data from 2007 to 2022, this paper takes the implementation of smart city policies as a quasi-natural experiment and uses the difference-in-differences method to examine the impact of smart city construction on regional energy mismatch. The results show that smart city construction helps to alleviate regional energy mismatch, and this effect is more obvious in southern cities, eastern cities, non-resource-based cities and non-old industrial base cities. The mechanism analysis shows that smart city construction can reduce the degree of regional energy mismatch by stimulating the vitality of urban green technology innovation, promoting the upgrading of industrial structure and the digital transformation of residents’ consumption patterns respectively. The research conclusions provide empirical evidence for relevant departments on how to ensure energy security and achieve the goals of sustainable development through the means of urban digital governance.