This article describes the Decision Support System (DSS) for identifying the best delivery methods for megaprojects, based on risk factors, opportunities for investments, and project constraints. In addition, the system accounts for the relative importance of various stakeholders’ roles at different stages of a mega infrastructure project. A fuzzy-based multi-criterion decision-making technique used to develop the DSS assists the client to depict his/her best choices of contractual delivery methods. Further, the system provides the best mix of stakeholder entities that would likely provide the best environment for the project success. A two-step system calibration procedure was considered, including the expert judgment of 192 key stakeholder professionals worldwide. The fuzzy model performance was illustrated using default factor sets and sample inputs of differing weights for project risks, constraints, opportunities and the other critical categories affecting the decision-making process. Based on model results, the conventional delivery method (e.g., Design Bid Build) is least recommended if the project risk weighs more than 30%, as provided by the user. With such an intricate system, the client can investigate the specifics of various project stages and study the effects of enhancements or deficiencies of the stakeholder entities’ capabilities.