This chapter aims to analyze the role of energy directives in ensuring energy security of the European Union, and to assess the current state of their implementation in the legislation of Ukraine in accordance with the Treaty establishing the Energy Community and the Association Agreement with the EU. The development of legal security of energy sphere in the EU from the Treaty of Paris on the European Coal and Steel Community to the fourth energy package, which allowed to provide the development of competition among producers and suppliers of energy resources, to provide equal access to the energy distribution and gas-distribution networks, to liberalize the energy sector and energy resources, to increase the use of green energy, to reduce emissions into the atmosphere, and to raise the level of energy security in Ukraine. In this chapter, the authors systematically analyze the implementation process of EU Energy Directives in the Ukrainian legislation using legal methods. They focus specifically on the Law "On Natural Gas Market", the Law "On Electricity Market", the Law "On Energy Efficiency", the Law "On Energy Land and Legal Regime of Special Zones of Energy Facilities", and the Energy Strategy of Ukraine till 2035 "Security, Energy Efficiency, Competitiveness".