The purpose of the study was to identify the main stages of development of the concept of neutrality to assess its effectiveness in the 21st century. The legal analysis of the Hague Convention of 1907 and the Geneva Convention of 1949, the content analysis of Politico, and the analysis of materials in the Digital Encyclopaedia of European History were used. The results of the study demonstrated that the concept of neutrality was formed in the times of ancient Greece and Rome. However, the rapid development of the concept is associated with the wars of the 18th and 19th centuries, especially the War of Independence and the American Civil War. In 1780, the League of Armed Neutrality was created, and in 1856, the Treaty of Paris was signed, which codified neutrality as a mechanism for ensuring international security. In the 19th century, there were also precedents that cemented the importance of neutrality, such as the Alabama Covenants. In 1907, important international conventions were adopted in the Hague, which emphasised the importance of neutrality and the rights of neutral countries in international conflicts. During the First World War, the concept of neutrality was adhered to by the US government. During the 1930s, the United States adopted legislation that regulated trade and economic relations with belligerent states. In the 21st century, the concept of neutrality is losing its relevance. Changes in the geopolitical situation, geographical proximity to Russia, which pursues an aggressive policy and does not respect international law, prompted the governments of Sweden and Finland to abandon the principles of neutrality and join the North Atlantic Alliance. The results of the study can be used to improve the international legal mechanisms governing neutrality and to develop foreign policy strategies of states in the current geopolitical environment