Sovereignty and self-determination are two principles accepted by UN in the UN Charter and resolutions. The aim of this thesis is to analyze the tensions between sovereignty and self-determination principles in the UN and to increase understanding of how these tensions might have led to ambiguity in UN policy toward the West Papua case. The thesis identifies that there are tensions between those two principles in the UN resolutions. The tensions cause ambiguity in the UN when they are involving in self-determination cases outside the classical colonial context. The argument will be strengthened by conducting a single case study analysis on West Papua self-determination claim. As one of the self-determination claims outside the classical colonial context, the UN role when being involved in the case is argued to be lack of response and ambiguous. It concludes that the ambiguity of the UN when involved in the West Papua self-determination claim is resulted from the tensions between sovereignty and self-determination principles in the UN resolutions.