This paper deals with the role of the United Nations in protection and preservation of refugees and migrants rights through the development of the institutions and legal rules under the United Nations and its predecessor of the League of Nations, but also the International Organization for Migration, which has spent a longer period of its engagement in independent action before it became a specialized agency of the universal international organization. The institutions, to which regulation, protection and preservation of the rights of refugees and/or migrants have been prescribed as the area of activity by the statute, are the backbone of this thesis which is focused on the documents that have come out from their activity. The basis of the refugees' rights is presented in the 1951 Convention Relating to the Status of Refugees, amended by the Protocol which has been created because of the political and social situations that caused inadequacy of the previously adopted document. While in the area of migrants' rights, only in the last two decades has there been an initiative to dispel the need to regulate this matter and to adopt political international documents in the form of the New York Declaration for Refugees and Migrants from 2016, which has served as the basis for a comprehensive Global Compact for Safe, Orderly and Regular Migration with still uncertain legality and legitimacy in implementation.