The article reveals questions regarding the professionalism of judges as an important prerequisite for efficiency (building an effective) judicial system in Ukraine. It has been established that today the main documents that regulate the legal foundations of professionalism of judges in Ukraine are the Law of Ukraine «On the Judicial System and the Status of Judges», the Concept of National Standards for Judicial Education in Ukraine, the Regulation on the Training and Periodic Study of Judges at the National School of Judges of Ukraine, as well as the Strategy development of judicial education in Ukraine for 2021–2025. It is determined that the professionalism of judges is based on the results of obtaining judicial education, which is aimed at acquiring the ability of judges to understand and behave fairly, authority and communication, the effectiveness of professional activity, personal qualities, and intellectual qualities. It was found that primary judicial education plays an important role in increasing the professionalism of judges, in particular, the training of candidates applying for the position of judges. It has been proven that in order to improve the professionalism of judges, it is also necessary to apply the latest forms and methods of training. It has been established that in order to improve professionalism in the administration of justice, judges must undergo special training to maintain their qualifications at the proper level. It was determined that for the purpose of professional development of judges, the National School of Judges of Ukraine has developed and operates various standardized training programs. It has been established that the main principles of training judges at the National School of Judges of Ukraine are the principle of versatility, comprehensiveness and focus on obtaining all the necessary skills and abilities, the principle of frequency, the principle of obtaining a more subjective vision of international practices in the administration of justice, the principle of uniformity, the principle of practical focus, the principle of high quality and scientific substantiation, the principle of modernity of training, the principle of initiative and interest of judges in improving their professional level, the principle of coordinating the activities of the elements of the training program, the principle of using modern innovative technologies in the training process, the principle of continuous education, that is, lifelong learning. It is noted that the prospects for further research in this direction are the study of the peculiarities of the formation of the corps of professional judges in Ukraine.