Brexit has an economic effect on both the UK and the EU. This paper is concerned with the economic impact of Brexit. UK chose the Hard Brexit to end its formal political and economic relations with EU. There are several economic causes of Brexit such as: The national interest, the financial crisis, the economic status of UK, the rising economic influence of Russia and globalization. The economic impact of Brexit on Britain varies from the British Direct foreign investments, British economic competition to fisheries. In addition to the economic impact on Northern Ireland. The cost of the Brexit will be paid in the future of economic relations between the UK and the EU and between the UK and the rest of the world.