Knowledge graphs are powerful tools that organize and connect information in a structured manner, enabling AI models to reason, infer, and generate insights with increased accuracy and efficiency. We have conducted extensive studies to explore the power of knowledge graphs in empowering AI applications, with a specific focus on recommendation systems and their broader implications. Specifically, knowledge graphs enable the integration of multiple AI techniques (e.g., information generation, retrieval, and recommendation), by providing a unified representation and facilitating knowledge-driven decision-making processes. We highlight real-world use cases where knowledge graphs have empowered diverse applications, including personalized recommendation in AI4E-commerce, and system analysis in AI4Security. Furthermore, we discuss how knowledge graphs empower AIGC.