After the collapse of the Soviet Union, the world has developed into a world situation in which the United States is the only super-Power and there are many powerful States. The United States had begun to successfully develop its hegemony in various areas of the world. However, the hegemony of the United States began to be challenged along with the re-emergence of forces in Asia and Europe. The opportunity of the Cold War was an important point in the formation of American hegemony. Because of this, the study of how American hegemony was formed during the Cold War and its impact on the world situation is crucial to how the United States faces the challenges that are now before it as well as the further development of the world situation. The main objective of this paper is to analyse how American hegemony was formed during the Cold War in terms of politics, economy, science and technology, and the impact of American hegemony on the world. The formation of American hegemony had a great impact on the US-Soviet relations, European integration and the development of the third world countries during the Cold War.