The reduction of energy carbon emissions and the increase in the number of vegetation carbon sinks play a crucial role in achieving China’s “carbon neutrality”. As a megacity, Beijing faces significant pressure to reduce carbon emissions and increase the number of carbon sinks because of its large number of individual buildings, high population density, overcrowded transportation, and enormous amount of human activity. Therefore, calculating and analyzing the carbon emissions, vegetation carbon flux, and spatial distribution in Beijing in recent years provide data that support energy conservation and emission reduction, urban fine management, ecological security pattern planning, and national land spatial planning, and contribute to the high-quality development of the capital. In this study, we applied the C-FIX model, referring to the “2006 IPCC National Greenhouse Gas Inventory Guidelines” and the “Provincial Greenhouse Gas Inventory Compilation Guidelines” compiled by China. The statistical yearbooks of different administrative regions in Beijing were referred to in calculating the energy consumption carbon emissions and vegetation carbon flux of Beijing in 2010 and 2020. The results show the following: 1) In 2020, the carbon emissions from energy consumption decreased by 36.78%, with the reduction of industrial energy consumption emissions playing a major role. 2) The demand for energy in residents’ daily lives significantly increased from 2010 to 2020, with the majority of the increase concentrated in areas with larger populations and more frequent activities. 3) Forest land in urban centers mostly serves as a carbon source, while in suburban areas, it serves as a carbon sink. The carbon flux of forest land in most areas shows an increasing trend, and the overall quality of forest land is good. 4) Grasslands in urban areas mostly serve as carbon sources, while those in suburban areas serve as carbon sinks. Moreover, the carbon sink capacity in most areas decreases, resulting in poor grassland quality. 5) The carbon absorption by vegetation is lower than the carbon emissions of energy, but the gap is significantly reduced.