Abstract: the emergence, formation and development of international economic integration occur under the influence of a number of factors. At the same time, states need funds and instruments that allow them to control integration processes by state authorities and direct economic integration. International economic integration is developing on the basis of foreign economic and foreign trade activities with direct participation in their regulation by the customs services. The optimal and balanced combination of economic, trade and customs diplomacy allows to ensure the systematic development of international economic integration, starting from the first stages of its establishment. Customs diplomacy is an important part in the system of means of implementing foreign economic and foreign trade policy, as well as an instrument for implementing international cooperation in the fields of international economic relations, international trade and customs. Interstate interaction, which is based on an integrated approach to professional diplomacy, including economic, trade and customs diplomacy, the development of international relations on a bilateral and multilateral basis, relying on an increase in trade between countries, coordinated financial and economic policies are the fundamental basis of international economic integration. Customs diplomacy ensures the balanced development of international economic integration, being the main tool accompanying trade and economic cooperation, as well as the means of the most stable interaction of state authorities of the uniting countries. The function of customs diplomacy that ensures international economic integration is confirmed by the practice of the emergence and development of a number of integration associations. In particular, economic integration in Europe, at the very beginning of its emergence in the form of an intersectoral union of states, was accompanied by customs regulation in the adopted documents. Customs support of European economic integration has become an integral basis, part of all the processes uniting the European states.
Keywords: international economic integration, foreign economic activity, foreign trade activity, economic diplomacy, trade diplomacy, customs diplomacy