Ultra-high speeds, low latency, and huge interconnectedness characterize the quick transition from 5G to 6G communication networks, which marks a revolutionary advance in wireless technology. With 6G, new applications, including the Internet of Everything (IoE), omnipresent AI, and holographic communications, will be supported. But since 6G has more capabilities, there will be a greater need for energy, thus energy efficiency becomes vital. With a focus on the salient characteristics of 6G networks above 5G and the urgent requirement for energy efficiency, this chapter offers an overview of the latter. Regarding sustaining high performance while reducing energy consumption, 6G networks will likely function worldwide with previously unheard-of data speeds and connections. To manage the complexity of 6G networks and provide creative solutions for energy efficiency, artificial intelligence (AI) is essential. The potential of AI-driven methods like federated learning, machine learning, and reinforcement learning to optimize network security, resource allocation, and predictive maintenance while consuming less energy is being investigated. Along with discussing trade-offs between performance, latency, and energy consumption, the chapter also explores the wider environmental and economic ramifications of attaining energy efficiency in 6G. The chapter shows how AI can drive energy-efficient solutions in various areas, from smart cities to autonomous cars, via case studies and real-world implementations. The chapter concludes by outlining future research prospects and discussing the legislative and standardization initiatives required to support the sustainable growth of 6G networks. It emphasizes the need for collaboration between AI and quantum computing.