Sub-Saharan Africa remains the region with the highest under-5 mortality (U5M) rates globally. Emerging evidence revealed that exclusive breastfeeding (EBF) rates are significantly associated with a decreased risk for child mortality. Our aim with this study is to fill the gap of knowledge regarding the economic impact of EBF practices in relation to U5M in sub-Saharan African countries. Data were gathered from the World Bank's database during the period 2000-2018. A meta-analytical approach was used to evaluate heterogeneity of country estimates and to perform an estimate of the prevalence of EBF and economic cost by country. The association between estimates of U5M and EBF prevalence was estimated and used to perform the total cumulative nonhealth gross domestic product loss (TCNHGDPL) attributable to U5M in 2018 and 2030. The prevalence of EBF increased by 1%, and U5M reduced significantly by 3.4 per 1000 children each year during 2000-2018. A U5M reduction of 5.6 per 1000 children could be expected if EBF prevalence improved by 10%. The TCNHGDPL in sub-Saharan Africa had a total value higher than $29 billion in 2018. The cost of U5M is estimated to increase to ∼$42 billion in 2030. If EBF prevalence improve by 10%, the related TCNHGDPL was estimated to be $27 billion in 2018 and $41 billion in 2030, therefore saving ∼$1 billion. Sub-Saharan Africa should imperatively prioritize and invest in essential approaches toward EBF implementation.