Nigeria’s agricultural sector remains a cornerstone of its economy, contributing significantly to employment generation, rural development, and food security. Despite this potential, the global competitiveness of Nigerian agricultural produce is hindered by persistent structural and institutional challenges. These include inadequate infrastructure, weak value addition processes, inefficient supply chains, limited compliance with international quality standards, and restrictive access to global markets. This study explores the multifaceted challenges affecting the international competitiveness of Nigerian agricultural exports, identifies emerging opportunities, and critically evaluates the policy implications for sustainable development. Adopting a qualitative approach and relying on secondary data, the study is anchored in Porter’s Diamond Model to analyze Nigeria’s agricultural sector through the lens of factor conditions, demand conditions, related and supporting industries, firm strategy, structure, and rivalry. Findings indicate that Nigeria’s poor logistics and transport infrastructure, inconsistent policy frameworks, and underdeveloped agro-processing capacity are central barriers to improving competitiveness. Moreover, quality assurance mechanisms and institutional support for exporters remain weak, limiting global acceptance of Nigerian produce. However, with strategic investment in infrastructure, innovation in agro-processing, regulatory reforms, and targeted international trade partnerships, Nigeria can reposition its agricultural sector for global relevance. The paper concludes by recommending coherent and export-driven agricultural policies, enhanced public-private partnerships, investment in value chains, and strengthened institutional frameworks to promote sustainable competitiveness of Nigerian agricultural products in international markets.