The spread of addictive behavior among minors continues to be a dangerous trend about children and young people. Therefore, one of the most important areas of pedagogical activity is the prevention of addictions in educational organizations, as well as the training of pedagogical university students for being able to prevent addictions in children and adolescents. The study considers the structure of pedagogical university students’ readiness for the prevention of addictions in the educational environment, relying on a competence-based approach. We have proposed a characteristic of the model for assessing the competence of future teachers in the prevention of addictive behavior in children and young people. We considered the content of the training of future teachers for the prevention of addictive behavior based on the study of preventive pedagogy, and analyzed the main approaches to the prevention of addictive behavior in the educational environment. We presented the results of an experimental study and revealed the effectiveness of the training of pedagogical university students for preventive activities with adolescents.