The relevance of the study is conditioned by the need to establish the genesis of legal regulation of the defence lawyer’s involvement in criminal proceedings against minors, to identify correlations of this process with the regulation of legal activity in Ukraine. The purpose of the study is to investigate the history of legal regulation of the involvement of a defence lawyer in criminal proceedings against minors. The study used a set of scientific methods: historical, historiographic, terminological, system-structural, formal-logical, and comparative-legal. It was established that the origin of the institute of protection of the parties in legal proceedings begins in the times of Kyivan Rus with the established practice of speeches in court by “good people” who represented the plaintiff and the defendant. It was proved that the development of the institute of protection of minors in court took place in parallel and in close connection with the development of judicial representation and sureties. Based on the analysis of international acts in the field of criminal justice against children ratified by Ukraine, the need to introduce juvenile specialisation of defenders was indicated. Stages of development of legal regulation of the defender’s involvement in criminal proceedings against minors: stage 1 – 1016-1529; stage 2 – 1529-1864; stage 3 – 1864-1917; stage 4 – 1917-1991; stage 5 – from 1991 to the present. The emergence of protection of the rights of minors in court was accompanied by the establishment of a regulatory condition for the involvement of a defender in the process on a gratuitous basis for certain categories of children. At the present stage, the law enforcement process embodies the principles and guarantees of involvement of a defender in criminal proceedings against minors, which are provided for by international treaties in the field of protection of children’s rights ratified by Ukraine. The proposed predictive trends in the development of legal regulation of the involvement of a defender in criminal proceedings allow law enforcement agencies to plan their practical activities in the interaction with human rights organisations, take coordination measures between juvenile prevention bodies of the national police, investigators and prosecutors specialising in the investigation of juvenile delinquency, juvenile judges and lawyers for effective compliance with international standards for the protection of the rights of children in conflict with the law.