Sub-Saharan Africa's low agricultural productivity exacerbates rural poverty. An important investment, the sustainable use of groundwater for irrigation, has the potential to increase agricultural productivity, but the region has been much slower to adopt this irrigation method compared to other regions, despite abundant reserves. This study uses a simulation-driven approach to examine the benefits of sustainably utilizing groundwater for irrigation. By mapping data from 291,798 global agro-ecological zones to 8,099 groundwater grids, the study models the production gains from groundwater irrigation for rain-fed croplands. Simulation results indicate that groundwater access could increase output by 27.97 to 129.42 percent, contingent on crop and model conditions. This research facilitates the assessment of the transformative potential of groundwater irrigation and identifies areas in Sub-Saharan Africa where investments can yield significant returns without depleting the groundwater table.