This chapter explores the theoretical foundations of complexity science, systems thinking, and artificial intelligence (AI) in managing modern decision-making challenges. It traces the origins and key concepts of complexity theory, such as emergent behavior, nonlinearity, and interdependence. The chapter then delves into systems thinking principles and frameworks, including feedback loops and causal loop diagrams. It also examines the role of AI technologies in enhancing decision-making processes by handling large datasets and identifying patterns. By integrating these approaches, the chapter provides a comprehensive understanding of how to navigate and manage complex systems effectively.