This article critically looks at the functioning of the best interest of a child principle in such Nigerian custody matters in the country's plural family law system. It employs a critical doctrinal-integrative review to examine the legislation, appellate cases, international and regional child-rights instruments, and recent peer-reviewed scholarship. Specific focus is paid to statutory law, customary law and Islamic family law, judicial discretion, parental rights, gender assumptions, cultural and religious issues and children's involvement. The review reveals that Nigerian law has a formal position, which puts child welfare at the centre of adjudication in the Matrimonial Causes Act and the Child Rights Act. The principle is up and down in practice where customary lineage expectations, religious customs that structure the custody of children, gender-based assumptions and limited avenues for hearing children shape decisions. The author does not believe that child-centred adjudication is at odds with legal pluralism; but whether there is a competing norm that is assessed in relation to the child's welfare or is left to decide matters for itself is the key question. It finally concludes that the welfare criteria need to be clearer, the participation rights greater and judicial practice needs to be consistent.