Nigeria is at a critical juncture in its digital transformation journey, with fifth‑generation (5G) wireless technology beginning commercial deployment and sixth‑generation (6G) on the research horizon. This article provides a comprehensive analysis of the adoption, infrastructure, regulatory landscape, and socio‑economic impacts of 5G/6G technologies in Nigeria. Using a mixed‑method approach combining primary stakeholder interviews (n=50) and secondary data from the Nigerian Communications Commission (NCC) and International Telecommunication Union (ITU) the study identifies key drivers: growing mobile broadband demand, smart city initiatives, and agricultural tech applications. However, significant barriers persist, including high capital expenditure for infrastructure, electricity unreliability, spectrum auction delays, and digital literacy gaps. The findings reveal that as of 2025, 5G coverage reaches only 35% of urban centres and less than 5% of rural areas. 6G remains at the conceptual stage, with potential for terahertz communication and AI‑native networks. The article presents a comparative table of 4G/5G/6G performance metrics in the Nigerian context. Recommendations include a public‑private partnership model for rural backhaul, a staggered spectrum pricing framework, and a national 6G research task force. This study contributes to policy design for emerging economies navigating next‑generation wireless deployment.