Sub-Saharan Africa faces persistent energy deficits despite abundant renewable resources, with the Horn of Africa offering exceptional potential for transformation through green ammonia (NH3) production. This study presents a comprehensive techno-economic assessment across four strategic sites: Ghoubet (Djibouti), Asmara (Eritrea), Addis Abeba (Ethiopia) and Mogadishu (Somalia). The specific contributions include: (i) comparative analysis of wind- and solar-based production systems, (ii) evaluation of alkaline electrolyzer efficiency impacts (50–66 kWh/kg), (iii) detailed LCOA assessment across investment scenario (2500–3000 kW), (iv) uncertainty and sensitive analysis over a 20-year horizon, (v) spatial mapping of production potential and (vi) multimodal transport logistics evaluation. Wind-based systems demonstrate superior performance, with Ghoubet achieving the highest output (1237 tons/year) at 50 kWh/kg electrolyzer consumption. Asmara leads in solar-based production (402 tons/year). Economic analysis indicates that Mogadishu and Ghoubet achieve the shortest payback periods (1.03 and 1.35 years, respectively). A 50 % production increase could reduce LCOA from 1195 to 438 $/tons in Djibouti. Furthermore, transport logistics significantly influence competitiveness: Ghoubet's multimodal connectivity provides the lowest wind-based export cost (740 $/tons). These results underscore the strategic importance of integrated renewable production and transport infrastructure for enabling cost-effective green ammonia production as a clean fuel, energy carrier and sustainable fertilizer.