This study focuses on theoretical and historical evolution of International Organizations. It also describes the basic objectives and significant role of international organizations in world politics. One of the most significant features of the twentieth century global politics has been the setting up and establishment of organizations, both at the regional as well as the international level. Their emergence and especially, their proliferation in the 20th century were largely facilitated, rather necessitated, by the rapid industrialization that revolutionized the transportation and communications networks within and among states, thereby reducing the physical world into a small unit and creating an unavoidable network of interdependence among states. Interdependence has stimulated the creation of international organizations and countries continue to come together to use this institutional framework as a means of promoting cooperation in social, economic, and political spheres. International Organizations have played and continue to play an important role in the international community. In the twentieth century two major experiments in global organization have been attempted, the League of Nations in the aftermath of World War–I and the United Nations following World War-II. International Organizations have become indispensable instrument within the International System.