This paper examines Nigeria's role in the regional integration process in West Africa through the Economic Community of West African States (ECOWAS) from 1975 to 2023. Nigeria's significant economic, political, and military influence in the region has positioned it as a key player in ECOWAS. This study explores Nigeria's contributions, challenges, and the impact of its policies on regional integration. Through a comprehensive analysis of historical and contemporary data, this paper provides insights into Nigeria's leadership and its implications for regional stability and development. The findings from the study revealed Nigeria's pivotal role in the regional integration process in West Africa through ECOWAS. Nigeria's economic strength, political leadership, and security contributions have been instrumental in shaping the trajectory of ECOWAS. The country's efforts in promoting economic integration, mediating conflicts, and supporting peacekeeping missions have significantly contributed to regional stability and development. However, the analysis also highlights several challenges that have impacted Nigeria's role. Economic vulnerabilities, domestic political instability, and regional rivalries have occasionally hindered Nigeria's ability to lead effectively. Addressing these challenges is crucial for Nigeria to sustain its leadership role and for ECOWAS to achieve its integration objectives.