China and India are heavily dependent on high carbon fossil fuels. This article elaborates on the implications of low carbon energy transitions in the two countries, which can mitigate their serious contribution to climate change while allowing economic growth. Three modelling case studies are presented: for the Chinese power sector; the economy of Beijing; and rural Indian households without access to electricity. They demonstrate a significant reduction in greenhouse gas emissions and energy use, while costs are likely to increase. The paper argues that financial assistance and technology transfer will be needed to support China’s and India’s efforts towards a climate-friendly low carbon economy.