This book contains the selected proceedings of the 2023 International Conference on Energy Engineering, held in Xi'an, China, December 15-17, 2023. The conference explores advances and practical applications in energy research and engineering, and delves into innovative approaches in four specialized tracks: New Transportation Energy, Power and Energy, Applied Thermal Energy, and Oil and Natural Gas Engineering. It explores strategies for accelerating the transition to renewable energy, optimizing power systems, harnessing thermal energy, and advancing oil and gas engineering practices. It benefits from a wealth of knowledge shared by academics and practitioners, fostering cross-disciplinary collaboration. The latest findings in electric vehicles, smart grids, thermal systems, and reservoir engineering will be explored to find solutions that promote sustainability, efficiency, and environmental stewardship.