The incidence of single motherhood, as an alternative family form, has been implicated in poor maternal and child health outcomes globally. In sub-Saharan Africa where these outcomes are poorest and where the global prevalence of single motherhood is the second highest, there is a paucity of studies on what drives single motherhood and how these drivers are influenced by variations at subnational levels. This study fills this gap in Nigeria. Data was extracted from the 2018 Nigerian Demographic and Health Survey on 3029 single and 28,888 married mothers. Associations were established using chi-square and binary logistic regression analyses. Single mothers constituted 9.5% of the population and, contrary to global patterns, were wealthier, more educated, and experienced less intimate partner violence (IPV). The prevalence ranged from 2.9% in the North-West to 20.3% in the South-South region. Age, IPV, being a Fulani, Hausa or Yoruba, and Islam lowered the odds of single motherhood while urban residence, education, wealth, number of children, and age at first birth increased the likelihood (P < 0.001). The relationships varied significantly at the subnational level. Nigeria has one of the highest prevalence of single mothers in the world and the prevalence pattern and sociodemographic correlates vary among ethnic clusters. Policy Implication The findings are important for policies to increase the acceptance of plurality of family forms and end discrimination against single mothers. They also point to improving maternal healthcare services in rural areas, where the bulk of the single mothers reside, for improved maternal and child health outcomes.