European Union’s accession to the Istanbul Convention together with the debates and competition among various actors with different choices on the subject constitute the primary focus of this study. The regional integration experience, which gained existence in Europe by the late 1950s, was extended into new policy areas with the transfer of power from member state to the Union level incrementally. Violence against women, as a shared problem of all the member states, became one of the areas in which the Union has acquired competences to develop policies and take actions throughout its lifespan. As a result of this shared responsibilities, the steps aiming to combat violence against women in Europe are taken with the policies and mechanisms developed and implemented both at the European Union and member state levels. The European Union’s accession to the European Council’s Istanbul Convention, which is frequently labelled as the most far-reaching and the only legally binding international law document about violence against women is an integral part of the Union’s activities in the field of violence against women. European integration has been shaped conventionally by the rivalry between the supranational and intergovernmental actors and has reflected the consequences of the balance of power among these actors. Therefore, the Union’s accession to the Convention can also be analyzed based on the supranationalism-intergovernmentalism duality perspective. In this vein, it is possible to define the actors supporting the European Union’s accession to the Convention as supranationalist and the actors having doubts related to the Convention as the intergovernmentalist and to argue that the contestation between these two groups of actors would be influential in the accession of the European Union to the Convention. The intergovernmentalist-supranationalist rivalry dimension of European integration is dealt with at the beginning of the study. Then the study elaborates on the Istanbul Convention and its role in combatting violence against women in Europe to get a better view of the European Union’s accession motivations. In the last section, the accession of the European Union to the Istanbul Convention, as well as the positioning of the supranational and intergovernmental actors are covered. The study aims to conclude by providing some insights about the European Union’s potential of becoming a party to the Istanbul Convention.