Conflicts between the right to respect for family life and the principle of the best interests of the child constitute a significant challenge in contemporary family law systems. This tension is particularly evident in custody disputes and in cases involving state intervention in family relations for child protection purposes. Article 8 of the European Convention on Human Rights recognizes the right to family life while permitting state interference only under limited and justified circumstances. In practice, the legitimacy of such interference is often assessed in light of the child’s best interests. Adopting an analytical and comparative approach, this study reconstructs the balancing logic developed in the jurisprudence of the European Court of Human Rights (ECtHR) and identifies the criteria applied by the Court in resolving tensions between these two principles. The analysis focuses on two landmark Grand Chamber judgments—Neulinger and Shuruk v. Switzerland and K. and T. v. Finland—and examines how the Court evaluates competing interests in cases concerning family separation and child protection. It also considers the compatibility of these judicial standards with the approach adopted in Iranian law. The findings suggest that the Court employs a flexible, case‑specific balancing framework based on factors such as the priority of the child’s interests, individualized assessment, emotional bonds, risk evaluation, and proportionality with procedural safeguards.