National and international courts are increasingly turning to generally recognised international legal principles to regulate private law relations. This is necessitated, in particular, by the fact that the issues and disputes that modern participants in private law relations address to the courts are becoming more widespread. Thus, the practice of international justice and justice in Ukraine demonstrates that such international principles as the principle of justice, equality, non-discrimination, evolutionary interpretation, proportionality, legal certainty, and the rule of law are increasingly used in dispute resolution. This study investigated the application of international principles in private law relations. Based on the general legal research methods, the nature of international legal principles was analysed, the study considered their application in the above-mentioned Ukrainian court cases to the European Court of Human Rights, as well as the Constitutional and Anti-Corruption Courts of Ukraine. The study investigated the judicial practice of the European Court of Human Rights, whose decisions raise the issue of violation of rights and fundamental freedoms stipulated in the Convention for the Protection of Human Rights and Fundamental Freedoms and non-compliance with basic international legal principles, as well as highlighted the main trends of these disputes. Based on the results of the analysis, the study identified an insufficient level of the content specification regarding the principle of the rule of law and its features in the current legislation of Ukraine, which must be properly observed by both state authorities and citizens of Ukraine. Based on the conducted research, the authors formulated their scientific positions and conclusions aimed at improving the system of principles of private law relations