The idea of 'hybrid sovereignty' describes overlapping relations between public and private actors in important areas of global power, such as contractors fighting international wars, corporations regulating global markets, or governments collaborating with nongovernmental entities to influence foreign elections. This innovative study shows that these connections – sometimes hidden and often poorly understood – underpin the global order, in which power flows without regard to public and private boundaries. Drawing on extensive original archival research, Swati Srivastava reveals the little-known stories of how this hybrid power operated at some of the most important turning points in world history: spreading the British empire, founding the United States, establishing free trade, realizing transnational human rights, and conducting twenty-first century wars. In order to sustain meaningful dialogues about the future of global power and political authority, it is crucial that we begin to understand how hybrid sovereignty emerged and continues to shape international relations.