Abstract While marriage has traditionally served as the connective tissue between fathers, mothers, and their children before the law, the increasing commonality of cohabitation-based relationships without marriage has led to many children being born outside of the marriage union. This has complicated the legal understanding of fatherhood in particular, which has traditionally relied on the contractual nature and stability of the marital union to be legally defined and understood. States are often ill-equipped to handle parental separation and child custody in the case of civil unions, and unmarried fathers tend to have fewer venues of legal protection compared to divorced fathers in that regard. The purpose of this article is to identify the legal challenges surrounding unmarried fathers and parental rights in the context of the jurisprudence of the European Court of Human Rights. It examines the elements of what constitutes legal fatherhood, identifies the main human rights issues surrounding unmarried fathers, and assesses the reasons for legal differentiation between divorced and unmarried fathers. Importantly, conclusions are drawn as to whether and why these differences are justified from a legal perspective. This article contributes to the need for more research in the area of father–child relationships and aims to provide guidance for policy and law-making with regard to unmarried parents in the context of children’s rights.