Children's participation in decisions about their lives is a crucial point of the UN Convention on the Rights of the Child, which is the basis of child welfare and protection worldwide. Despite these clear guidelines, there is evidence that children's voices may be heard but often with little impact on the decisions made by professionals in the childcare system. This study seeks to ascertain whether the voice of children living in foster care is considered and respected when making decisions that concern them, whether the children effectively exercise it, and what factors impact their participation. A systematic scoping review was performed to clarify concepts and unveil research gaps, using eleven scientific databases and publishers that allowed us to identify twelve recent studies in critical journals. In the light of the Bouma et al., (2018) model, the findings showed that there is, in general, a lack of effective children's participation, namely in terms of information, listening, and involvement. Children's voices still have a minimum impact on the decisions made in the childcare system. It will be necessary to avoid the bureaucratic assumption that there is an age cut-off point to promote participation. More, it is stressed the importance of a trusting, sincere and confidential relationship between the child and the social worker and the need to ensure training for professionals who intervene in review/statutory meetings or judicial proceedings, namely in the court of law.