The aim of this study was to analyze the relationship between participation and mental health of children and adolescents according to the perceptions of professionals working in the protection system in Chile. Fifteen semi-structured interviews were conducted with 8 psychologists and 7 social workers (10 women and 5 men between 27 and 55 years old) belonging to the regions of Valparaíso, Metropolitana, Araucanía and Magallanes. A thematic analysis was carried out through an interpretative process of the data by constructing categories of analysis. It was found that among the professionals there is a low consensus regarding the concept of participation; that a contextual view of mental health prevails; and that they share the idea that the relationship between participation and mental health of children and adolescents is mainly given by the influence of participation on their mental health. Based on this, there is a need to generate new training and/or instances of reflection for professionals in the protection area where the idea of the reciprocal impact between participation and mental health of children and adolescents is strengthened. The need to include specific mechanisms to facilitate child participation in the technical guidelines of the programs is also proposed. As a projection for future research, it is necessary to explore the effective implementation of participation practices in future studies.