Background: Teen pregnancy and childbearing are common in Nigeria, and understanding the complexities, such as sociodemographics and economic factors including sexual and reproductive health knowledge and awareness among adolescents over time can trigger innovative approaches and interventions. This study intends to capture the patterns and associated factors of teen motherhood among sexually active adolescents (15–19 years) between 2008 and 2018. Methods: The study data was extracted from 2008, 2013, and 2018 Nigeria Demographic and Health Surveys. Descriptive analysis was presented using frequencies and percentages; multivariable analysis was conducted using log-binomial logistic regression at a p-value <0.05. All analyses were performed using Stata 15.0, weighted and adjusted for the complex survey design and population size. Results: The prevalence of teen motherhood increased between the three successive survey waves (50.9% vs.Ìý52.4%Ìývs. 55.2%) from 2008, 2013, and 2018. Although, the pooled adjusted analysis revealed no significant change over the 10-year period. Knowledge of modern contraceptive methods, primary education, non-Catholic Christians, residing in the South-South region, and those currently or formerly married were associated with increased risk of teen motherhood. There was an inverse relationship between teen motherhood and wealth status; lower wealth status was associated with high adolescent pregnancy and childbearing. Conclusion: This study revealed an increase in the proportion of teen pregnancy and childbearing in Nigeria. Notably, there exist variations across age groups, geographic location, educational level, religious belief, marital and economic status. Interventions that ensure comprehensive sexuality education, girl child education, and economic empowerment especially for school dropouts are advocated to reduce teen motherhood.