Sudan, one of the largest countries in Africa, gained its independence in 1956 after the British colonial period. After the independence, it experienced unstable periods, civil wars and conflicts with both the problems from the colonial period and political conflicts, ethnic (Arab-African) and socio-cultural (religion, regional nationalism and tribalism) problems. Many people died or were harmed as a result of the civil war between the North (government forces) and the South (Sudan People's Freedom Movement etc.) and the conflicts in Darfur. This process in Sudan led the UN and other international organizations to take an interest in Sudan, and with the Comprehensive Peace Treaty signed in 2005, South Sudan gained its independence with a referendum held in 2011. However, this referendum process was not so easy. In Sudan, the UN made intense efforts to ensure international peace and security with the decisions it took after 2000 and the missions it created. In order to prevent conflicts, deaths and humanitarian crises between the North and the South, many decisions were taken in the Security Council, UNAMIS and UNMIS missions were established, and special representatives were appointed. Despite these measures, including peace processes, administrative measures, security measures and humanitarian aid, the structure of Sudan could not be preserved, and the country was divided into two with a referendum held in 2011. In this article, in which the United Nations (UN) mission in Sudan will be discussed in detail, it is hypothesized that the UN's efforts to ensure international peace and security in Sudan failed, and as a result, Sudan was divided into two in 2011. is being driven. In the study, the process of ensuring international security and peace in Sudan is discussed with its historical, legal, socio-cultural and security dimensions. [ABSTRACT FROM AUTHOR]