Additional education, along with school education, is becoming an important link in the general education system, which guarantees the formation of the student’s personality and his or her early professional self-determination. For this reason, all the methods and techniques used by teachers of additional education in their practice should form competencies that meet the requirements of modern society. Nowadays, with a wide variety of forms in the additional education system, project activities are one of the most demanded and innovative areas. This article reveals the main goal of the study of theoretical substantiation and experimental verification of the effectiveness of the pedagogical conditions for organizing the project activities of students in the additional education system. The methodological basis of the study is as follows: the main provisions of the personality-oriented approach; theoretical foundations of the competency-based approach; the provisions of the activity approach. The scientific novelty of the research lies in the fact that a complex of pedagogical conditions was developed that is necessary and sufficient for the effective implementation of project activities in an additional education institution for children. The result of the research is as follows: the developed theoretical provisions and conclusions enable to modernize the organization and content of project activities in the additional education system; a set of pedagogical conditions for implementing project activities of students in the additional education system has been developed. The research results can be used in the work of additional education institutions for children, as well as in other educational institutions.