Environmental sustainability is a crucial issue for all human beings, and vehicle emissions significantly contribute to climate change. This has prompted many countries, including China, Norway, and Germany, to focus on electrifying transportation. This study quantifies the life cycle carbon dioxide (CO₂) emissions of electric buses (EBs) in Guangzhou, China, via a life cycle analysis methodology, revealing an average life cycle emission of 1,097.07 g CO₂·km⁻¹·vehicle⁻¹. The operation and charging stage contributes the most to the lifespan of CO₂ emissions at 69.6%, driven by carbon-intensive power grid. Compared with conventional internal combustion engine buses, EBs result in significant emission reductions, but regional grid carbon intensity variations across China mean that their benefits depend on nationwide green energy adoption. By 2030, emissions are projected to decline by 15.28%, aligning with carbon peak goals. The findings emphasize that transitioning to renewable energy grids and hybrid technologies is critical for sustainable transportation.