Energy use in Bangkok accounts for a large portion of the total energy consumption in Thailand. Few energy and carbon studies, however, have focused on the level of the city. International research indicates that cities are the key drivers of energy usage and the associated carbon emissions. This paper presents a study on the options for energy and carbon development for the city of Bangkok. The Long-range Energy Alternatives Planning System (LEAP) model is used to simulate a range of policy interventions and to predict how these would change energy and carbon development from 2000 to 2025. The planning period is assumed to start in 2005, and 2000 is used as the baseline year. Sustainability of the sixteen proposed policies and scenarios is analyzed using a multi-criteria decision-making approach. Results of this study provide an insight into Bangkok's energy and carbon future and highlight the steps required to promote a sustainable low-carbon society. The most significant energy savings are in the transport sector, where a modal shift from private passenger vehicles to mass transit systems has the potential to significantly reduce energy demand, carbon emissions, and local air pollutants.