Perceived failures by the U.N. Security Council have been characterized as “betrayals of trust,” which threaten to impact the strength of the Council’s authority. In certain legal cultures, fiduciary law has been recognized as an effective legal mechanism to underwrite trust in the exercise of authority. This Article considers the potential value in applying the fiduciary construct to the Security Council setting as a way to consolidate trust. In doing so, it is necessary to unpack two different conceptions of the fiduciary construct: the precept of law (derived from domestic private law) and the precept of authority (sometimes described as public fiduciary theory). Interpreting the former precept as applicable to private interests and the latter to the public interest, this Article recognizes both precepts as applicable to relationships in which there is a legal expectation that those exercising control over another’s interests will not exploit (duty of loyalty) or squander (duty of care) those interests. The central question is whether the U.N. Security Council can be said to exist in such a relationship, either with private individuals or entities or with some iteration of the international community more broadly. By reference to recent controversies, including privatization of public assets in Kosovo, sexual exploitation and abuse by U.N. peacekeepers, Security Council vetoes in the face of atrocity and due process failures in sanctions decision-making, this Article examines the extent to which the fiduciary construct can play a useful role in reinforcing trust in the Security Council setting.