This work examines the issues of consolidation of customary law in medieval Hungarian sources. The relevance of the study of customary law as the most important part of the socio-normative culture and the traditional legal regulator, normatively fixing ethnic identity, expressed not only in the national-cultural worldview, but also in the written medieval Hungarian sources that operated for many centuries, starting from the origins of the creation of the Hungarian state until the beginning of the XVI century, no doubt. The aim of the work is to study customary law, its institutions in the sources of law of medieval Hungary. The novelty of the research lies in the fact that it analyzes the empirical historical and legal material, which makes it possible to identify the institutions of customary law in the medieval Magyar sources of law. In a comprehensive study of customary legal aspects, in Hungarian sources of law, it is important to be guided not only by the formational approach, which makes it possible to understand the changes that took place in the medieval period, during the emergence and development of feudal relations in the Western European state, but also by the civilizational approach, revealing the historical, political, socio-cultural components of the feudal Christian state. The methodological basis of this research is formed by a system of cognitive methods developed by various modern sciences. Thanks to the application of the systemic method, the customary law of the Hungarian people is important to consider as an element of the legal space of Hungary as a Central European state. The study shows that the Hungarians had a law as their initial act. Many Hungarian customs and customary legal institutions found their fixation precisely in written sources of law.