Land cover changes are the main causes of carbon emissions and ecological damage, so accurate land cover data are essential for precise carbon emissions estimates. The Dempster–Shafer (D-S) evidence theory was used to fuse three sets of 30-m land cover data: China’s National Land Use and Cover Change (CNLUCC), Global 30-m Land Cover Classification with a Fine Classification System (GLC_FCS30), and the China Land Cover Dataset (CLCD), to product high-precision land cover data, and carbon emissions were calculated based on carbon emission factor method in the Yangtze River Delta (YRD) from 1990 to 2020. The results show that (1) the average annual accuracies of the three products, CNLUCC, GLC_FCS30, and CLCD, are 64%, 78%, and 76%, respectively, with CLC_FCS30 showing higher classification accuracy. (2) The D-S evidence theory as a fusion method effectively integrates multi-source land cover data, enhancing the overall accuracy of the fused data by 11% to 22% compared with the original data. (3) Carbon emissions in the YRD region reached 594.043 million tons by the end of 2020, marking an increase of 468.480 million tons since 1990. Notably, there is a significant spatial variability in carbon emissions, with coastal areas exhibiting higher emissions, and a shift toward inland regions. This can serve as a valuable reference for urban planning and environmental conservation in the YRD region.