This study examines the nexus between public debt, governance quality, and human capital development in Nigeria from 1996 to 2023. Using advanced econometric techniques, including the Autoregressive Distributed Lag (ARDL) model methods, the research investigates three key areas: the direct impact of public debt on human capital development, the effect of debt servicing on human capital outcomes, and the mediating role of governance quality in shaping these relationships. Empirical findings reveal that public debt and debt servicing exert significant negative effects on human capital indicators, particularly in education and health sectors. However, governance quality—measured by institutional effectiveness, control of corruption, and regulatory quality—plays a crucial role in mitigating these adverse impacts. The study confirms that strong governance frameworks enhance the productive use of public debt, ensuring that borrowed resources contribute positively to human capital development. Conversely, weak governance exacerbates the crowding-out effects of debt servicing on critical social investments. The study recommends strengthening debt sustainability frameworks, enhancing institutional effectiveness, combating corruption, reinforcing legal and regulatory systems, and channelling debt toward education, health, and related sectors.