With the signing of the Paris Agreement in 2016, countries began to explore new economic models to get rid of the high emissions and high pollution caused by the traditional extensive economic model. Circular economy (CE) is regarded as an important way to achieve carbon neutrality, yet there is little literature has explored the relationship between the two. This paper aims to provide evidence and suggestions for developing circular economy strategies in emerging developing countries such as China by exploring the relationship between circular economy and carbon emissions. In this study, urban carbon emissions were measured by using high-resolution carbon emission data and the circular economy of 285 cities in China from 2009 to 2018 was estimated using a data envelopment analysis (SBM-DEA) model based on a super effective slackness measure. Then, the spatial impact of the circular economy was analyzed based on the spatial Durbin model. The empirical results are as follows: first, carbon intensity shows a positive spatial correlation, with most cities clustered in high-high (H-H) and low-low (L-L) types. Second, it was found that CE has a significant negative impact on the carbon intensity of local cities and neighboring cities. Third, based on regional heterogeneity, CE has significant negative direct and indirect effects in central and western cities. In contrast, CE has only significant direct effects (negative values) in eastern cities.