Persistent governance failures in public construction projects highlight the need for strategic interventions, with Civil Society Organizations (CSOs) providing a potential pathway toward more transparent, inclusive, and sustainable infrastructure delivery. This study investigates the factors influencing the effectiveness of CSO oversight in Nigeria’s construction sector and explores strategies for strengthening their role. Data were collected through a survey of 305 respondents—including CSO staff, government officials, and project beneficiaries—and analyzed using mean score and the Kruskal–Wallis rank test. Findings indicate that CSO oversight is constrained less by technical limitations than by structural and political barriers. Limited information access and weak coordination are further compounded by entrenched patronage, institutional fragmentation, and low civic legitimacy. The study also shows that meaningful contributions to accountability and inclusive governance depend on aligning foundational, operational, and adaptive strategies. Addressing these challenges requires more than transparency tools, calling for broader political and institutional reforms. The study recommends strengthening CSO oversight through legal and regulatory safeguards, diversified and sustainable funding, enhanced technical capacity, and context-sensitive collaborative approaches.