With China’s dual carbon goal leading to a surge in demand for clean energy and natural gas, Southeast Asia’s abundant oil, gas, hydropower, and wind and solar resources have become a new focal point for bilateral cooperation. Under the frameworks of the Belt and Road Initiative and the ASEAN Plan of Action for Energy Cooperation, China and Southeast Asian countries are forging a deep integration of “resource-channel-market” connections. On the one hand, cooperation between China and Southeast Asian countries in the conventional oil and gas energy sector continues to improve, with Chinese and Southeast Asian companies continuously expanding collaboration to jointly tap into the value of the entire traditional supply of energy chain, extend the mid-and downstream oil and gas supply chains, and leverage the advantages of the “oil and gas plus” model. On the other hand, China and Southeast Asian countries are continuously expanding cooperation in the new energy sector, with Chinese companies actively participating in related new energy projects across a wide range of areas, including photovoltaics, energy storage, carbon capture, and hydrogen production. This chapter focuses on the two dimensions of conventional oil and gas energy and new energy, systematically examining the evolution of cooperation, landmark projects, policy and institutional innovations, and current challenges. Based on this, it also envisions the sustainable prospects for regional energy security and green transformation, providing new perspectives for the development of a China-Southeast Asia Energy Community.