The preconditions for the research are based on sustained trends of the influence of development rates of digital economy, information space in Belarus on dynamics of digital transformation of additional education of children and youth (AECY). Analysis of AECY digital transformation revealed specific properties of didactic singularity of information education environment, network clustering of resources, dynamics of media environment contour, e-technologization of didactics. The established preconditions of stability of AECY digitization as a constant of transfer to regulations predetermined the aim of this work: development, substantiation of methodological concepts of AECY digitization. The research methods included theoretical and empirical analysis, expert appraisals, simulation, forecasting. The results are comprised of development of a set of organizational and network, environmental, instrumental, technological, institutional concepts of scientific methodology of AECY digitization. The obtained results were verified in the project titled “Implementation of Republican methodological cluster as a resource of development of additional education of children and youth” (2017-2020) on the premises of National Center of Artistic Activity of Children and Youth (Minsk) in accordance with the Program of innovations of the Ministry of Education, Belarus. The novelty of the results is in introduction of the following categories into scientific usage of pedagogical science: didactic singularity of information and education environment, structure of media environment contour. The novelty of the results is reflected in authentic intelligent product of scientific and practical significance in the context of Belarus National Strategy of Sustainable Social and Economic Development–2030.