This chapter examines systemic decision-making in complex environments. Adopting a systemic mindset allows us to perceive the world as a network of interconnected elements. It explores system models, such as input–output models and causal loop diagrams, to illustrate how relationships and interactions shape outcomes. The discussion also introduces key decision analysis techniques, including decision trees, Bayesian decision theory, and soft systems methodology. Additionally, it highlights the role of big data and artificial intelligence in analyzing intricate systems and enhancing decision-making in dynamic environments.