Child custody is one of the most significant issues in family law, playing a decisive role in a child’s life. In this context, the forfeiture of a mother’s custody right due to remarriage has received considerable attention in Imami and Sunni jurisprudence, and consequently in the laws of Islamic countries. Using a descriptive-analytical method and library-based data collection, the present study comprehensively examines and critiques the views of Imami jurists and the Sunni schools of law (Hanafi, Maliki, Shafi’i, and Hanbali). Accordingly, three main perspectives are addressed: the absolute forfeiture of the mother’s custody right upon remarriage, the absolute non-forfeiture of this right, and the view of differentiation (tafsīl). In Sunni jurisprudence, the predominant view holds that the mother’s custody right is forfeited only if she marries someone who is not a relative of the child. Relying on the Munqirī tradition, the author proposes the theory of differentiation between the father’s being alive or deceased as the preferred (mukhtār) position