Objectives: This study aims to investigate children’s experiences regarding their involvement in the justice system and explore the different facets of their participation, the mechanisms and practices applied, and criticisms and improvements to the justice system. Materials and Methods: A systematic review was conducted through consultation with EBSCO, Web of Science, Pubmed, and PsycArticles. Five articles were included to understand the perspectives of professionals, children, and young people regarding their participation in the justice system. Results: The children and young people involved in the justice system have negative experiences with its professionals, who doubt their ability to understand, devaluing their opinions. The children give up expressing their experiences, reducing participation and creating barriers with professionals. The children say that greater encouragement from judges reduces stress and makes the process more comfortable, increasing their participation. The professionals reveal that the mechanisms used in the system reinforced this lack of participation, despite its initial objective of integrating and including children and young people in the justice system. In general, the child’s legal guardians are better informed about their rights and procedures and have a greater opportunity to give their opinions than children and young people. Conclusions: Despite the advancement and improvement in procedures and mechanisms used to ensure children’s participation, they still have negative experiences about the system itself and the professionals, which reduces their participation.