<p>Energy consumption rights trading, as a market-based environmental regulation measure for source governance, is an important policy to help achieve the “dual carbon” goals. Based on the panel data of 260 cities in China from 2007 to 2022, the difference-in-differences method was used to explore the impact effect and mechanism of the implementation of the energy consumption rights trading pilot policy (ECRTP) on carbon emission intensity (CEI). The research findings are as follows: (1) the pilot policy of energy consumption rights trading has effectively reduced CEI in the pilot areas and played a positive role in market-based environmental regulation. This result remains valid after a series of robustness tests such as endogeneity test, parallel trend test, PSM–DID test, and placebo test. (2) The results of the mediating effect test first show that ECRTP mainly achieves CEI through two channels: promoting industrial structure upgrading and optimizing the energy structure. (3) Heterogeneity analysis reveals that the impact of ECRTP on CEI is more significant in mature and growing resource cities as well as in the central and western regions. The above conclusions provide important empirical evidence for further promoting the stable development of the national carbon trading market, giving full play to the positive role of market-based environmental regulations, and advancing the realization of the “dual carbon” goals.</p>