Although the legal institute of the exclusive economic zone was officially established by the 1982 UN Convention on the Law of the Sea, its development began through international customary law. This paper examines the historical, political and legal factors that influenced the development of the exclusive economic zone through customary law and how it gradually became an integral part of the modern law of the sea. Developing countries played a significant role in this context by expanding their jurisdiction in the high seas to protect their natural resources from developed countries. The idea of a new, 200 nautical miles wide, economic zone in which a coastal state has special rights, spread around the world, and in the 1970s, during the Third UN Conference on the Law of the Sea, the exclusive economic zone was accepted as a part of international customary law, and was codified by the 1982 UN Convention on the Law of the Sea. Therefore, the central part of this paper provides a detailed analysis of the legal regime of the exclusive economic zone under the provisions of the UN Convention on the Law of the Sea, with the focus on sovereign rights and jurisdiction of coastal states, as well as the rights and obligations of other states. Finally, the paper discusses the historical development of the legal regime of the exclusive economic zone in the Republic of Croatia and the latest events in this area over the past few years. Croatia first declared only a part of the content of the exclusive economic zone in its "protected ecological and fishing zone" in 2003, which caused diplomatic tensions and a delay in its implementation until an agreement was reached. After joining the European Union and negotiations with neighboring countries, Croatia declared its exclusive economic zone in 2021.