The article is devoted to the analysis of the constitutional principles of implementation of the Association Agreement between Ukraine and the European Union. It is determined that the important factors of constitutional support for the implementation of the Association Agreement between Ukraine and the European Union are, first, the consolidation of the pro-European foreign policy of the state, which is a kind of constitutional guarantee of continuity and consistency in implementation and association activities in Ukraine EU and, secondly, the improvement of constitutional provisions on the interaction of national and international law, in particular those governing the implementation of international treaties into the national legal system. Attention is drawn to the need for more systematic constitutional and legal regulation of international and domestic law, in particular, it is proposed to include in the formation of a «package» of systemic constitutional changes, items on the relationship between international and national law, which will create the basis for: 1) to consolidate the superiority (primacy) of properly implemented international legal norms over the national law of Ukraine (except for the Constitution of Ukraine, which should have supremacy and priority in the national legal system); 2) to regulate the application of other sources of international law in Ukraine (first of all, generally accepted principles and norms of international law, as well as acts of international organizations); 3) specify the forms of expressing consent to the binding nature (methods of implementation) of an international agreement for Ukraine; 4) determine the place of international treaties of Ukraine in the hierarchy of normative legal acts; 5) to expand the range of subjects of implementation of international agreements and to regulate the status and hierarchy of intergovernmental and interdepartmental agreements accordingly. The ongoing process of constitutional reform in Ukraine creates a legal basis for the systematic elimination of shortcomings and gaps in the Constitution of Ukraine in the field of interaction between national and international law. Key words: Constitution of Ukraine, Constitutional Reform, Constitutionalization, European Union, Association Agreement between Ukraine and the EU, Implementation.