In the era of carbon peaking and carbon neutrality, it is of great significance to explore the impact of land use change on carbon emissions and its impact path for promoting coordinated ecological and environmental governance and achieving green and high-quality development. Starting from the perspective of the conversion of cultivated land into construction land, based on the data of 224 prefecture-level cities in China in 2009-2010 and 2018-2019, this paper uses the panel fixed effect model to focus on the carbon emission effect of the conversion of cultivated land into construction land and its influencing mechanism. The results showed that: (1) the conversion of cultivated land into construction land showed a shrinking trend, and the eastern provinces and northeast regions had the most prominent trend, while the central and western provinces had no obvious shrinking trend. The total carbon emission showed a downward trend only in the eastern provinces, while the other provinces showed an upward trend. (2) The conversion of cultivated land to construction land significantly increased carbon emissions, and this research result remained valid after robustness test and possible endogeneity treatment. (3) The change of industrial structure and energy consumption caused by the conversion of cultivated land into construction land is the main path affecting carbon emissions.