The rule of law is one of the fundamental principles endorsed by modern states, international organisations and supranational structures. The principle of the rule of law has been shaped by national experiences in the historical process, and it is used in different contexts depending on the subjective experiences of nations. The term the rule of law has started to be used within the context of international legal order with the reconstruction of the international order, especially after the Second World War. The establishment of supranational political structures such as the European Union has revealed the need to determine the rule of law’s content in a more concrete way to ensure its applicability to the activities taken by these supranational structures. At this point, there is a need to interpret the principle of the rule of law uniformly to eliminate the differences in meaning at the national level and to bring it into a common meaning and content within the EU order. For this reason, first, it is necessary to define the principle of the rule of law from a philosophical perspective. Then, the study examines the existing national experiences in the supranational order and explores the essence of the principle and its perception at the international level. By doing so, what kind of meaning is attributed to the principle of rule of law within the EU will be answered and the scope of the principle within this framework will be determined. Addressing the principle of rule of law in this way is important to understand this fundamental principle, which is frequently on the EU agenda with the recent developments and has a vital importance.