All states, whether governed by liberal or illiberal regimes, face the prospect of momentous and potentially catastrophic environmental impacts due to climate change. Historically, energy policy has been directed towards simply achieving energy security. This goal has now been significantly complicated by the need to achieve it while minimizing greenhouse gas emissions. Environmental non governmental organizations (ENGOs) could play a crucial role in promoting the transition to energy and climate security but the relative (il)liberalism of the political regime they operate under influences their effectiveness. This article assesses how ENGOs have impacted on the transition to energy and climate security in Myanmar and Thailand, two Southeast Asian countries highly susceptible to climate impacts and characterized by illiberal rule. It finds that the impact of ENGOs was highly dependent on their strategies, tactics and operation, with community-level projects providing a key route to effect change under conditions of extreme illiberalism.