India's contributions to meeting global mean temperature increases of 2 °C or well below 2 °C would require transformational changes in its energy systems. A bottom-up model analyzes alternate futures (reference, intended nationally determined contributions and low-carbon scenarios) assuming equal per-capita cumulative emissions rights from 2011 through 2050. The cumulative CO2 budget for India for low-carbon scenarios during this period is estimated to be around 115 Bt-CO2, as against 165 Bt-CO2 for the reference scenario. To achieve such emission reductions, while maintaining high economic growth and meeting sustainable development goals, the paper projects that a range of endemic transformations are required such as shifting toward cleaner fuels, resource efficient technologies, widespread use of Information and communication technology (ICTs) to balance demand and supply (e.g. smart grids), substituting demand in transport (e.g. work from home), aggressive promotion of renewables, lifestyle changes, and CO2 capture, storage and use. Modeling decarbonization to meet the needs of the increasing population and urbanization faces myriad challenges due to the distributed nature of technologies used to provide various services, involving risks and uncertainties. The paper finally outlines specific opportunities and challenges faced to meet the increased mitigation ambition to limit the warming to 2 °C and below.