This article discusses whether and how the best interests of the child, enshrined in Article 24(2) of the Charter of Fundamental Rights, became an instrument for increased protection of the rights of migrant children and their families in the European Union. First, an overview is presented of the temporal and substantive expansion of the case law of the European Court of Justice reflecting on the use of references to Article 24(2) of the Charter. Then, a range of issues is analysed concerning the interpretation of the legal instruments of the Common European Asylum System, the Family Reunification Directive, and the Return Directive. The ECJ decisions are grouped by sub-topics and presented in chronological order. This analysis allows for a reflection of the evolution of the Court’s interpretation of the best interests of the child in this field of Union law. It is observed that the primary consideration of the best interests of the child is gradually becoming, if not a general principle, at least a safeguard principle for the genuine enjoyment of the substance of children’s rights.