The nexus between tax revenue mobilization and human capital development in Nigeria has raised concerns, despite extensive research and ongoing debates among stakeholders. While developed countries have studied the impact of tax revenue and institutional quality on human capital extensively, there is limited research in developing nations like Nigeria. This study, therefore, examined how oil and non-oil tax revenues affect human capital development in Nigeria, covering 2011Q1 to 2024Q4, using institutional quality as a moderating factor. The study employed the Dynamic Ordinary Least Squares (DOLS) estimation technique for data analysis and found that both oil and non-oil tax revenues contribute significantly to human capital development, but only over the long run. The institutional quality had an insignificant short-term influence but a significant positive long-term effect on human capital development. Moreover, institutional quality was found to positively moderate the relationship between both oil and non-oil tax revenues and human capital development over the long term. The study concluded that oil and oil tax revenue mobilization were significant drivers of human capital development in Nigeria, with their positive effects further strengthened by institutional quality in both the short and long run. Based on these results, the study recommends efficient allocation of tax revenues through targeted investments in education, healthcare, and skills training and also calls for reforms in tax policy and stronger institutions to maximise long-term human capital development.