Background: Notwithstanding government efforts in improving maternal and child health, childhood mortality still remains a serious burden in the country, with neonatal mortality rate of 39 deaths and under-five mortality rate of 132 per 1,000 live births. This has implication on Sustainable Development Goals (SDGs) targeted towards reducing under-fiver mortality rate to 25 deaths per 1,000 live births by the year 2030. This study examined risky fertility behavior, breastfeeding practices, and neonatal mortality risk in Nigeria. Materials and methods: This study involved the analysis of secondary data, Nigeria Demographic and Health Survey (pooled dataset of the three most recent surveys, NDHS, 2008, 2013 and 2018). The sample size was a weighted sample of 94,062 women aged 15-49 years with 172, 252 live births for the ten years period. Descriptive statistics and cox-proportional hazard model were performed using Stata 14.1 software. Results: Nearly two thirds (64.0%) of births were high risk. The practice of breastfeeding among the women was quite poor, just (39.5%) initiated breastfeeding within one hour of childbirth, though (74.0%) reported breastfeeding their child for a minimum of 12 months. The independent effect of risky fertility behavior (RFB) was associated with elevated hazards of neonatal mortality, with the highest risk observed among births belonging to the multiple high-risk group (HR=2.1, p<0.01). Adjusting for breastfeeding practices, maternal/child characteristics and maternal health seeking behavior was associated with elevated hazard of neonatal mortality with the highest hazard observed among births belonging to the multiple high-risk group (HR=1.76, p<0.05). Other factors associated with elevated hazard for neonatal mortality are sex of the child, maternal level of education and breastfeeding duration. Conclusion: RFB was associated with elevated hazard for neonatal mortality, even after adjusting for breastfeeding practices, maternal and child characteristics and maternal health-seeking behavior thereby lending credence to Mosley and Chen theory.