This paper investigated the impact of military expenditure on human development outcomes in Nigeria, focusing on the disaggregated components of military spending, recurrent military expenditure, capital military expenditure, and foreign military aid, between 1999 and 2024. The paper employed the Dynamic Ordinary Least Squares (DOLS) estimation technique. The empirical findings revealed that recurrent military expenditure had a positive and statistically significant impact on HDI, suggesting that routine defence spending contributed to national stability, which in turn enhanced the delivery of social services. In contrast, capital military expenditure exerted a significant adverse effect on Human Development Index (HDI), implying that large-scale investments in military infrastructure and equipment may have diverted resources from critical social sectors. Foreign military aid had a positive and significant effect, though of smaller magnitude, indicating that when wellcoordinated, military assistance from external partners could support security conditions conducive to human development. Based on these findings, the study recommended that the Federal Ministry of Defence and the Ministry of Finance should sustain and enhance the efficiency of recurrent defence allocations while ensuring transparency and accountability. It was also recommended that the Budget Office of the Federation and relevant committees in the National Assembly rigorously evaluate capital defence projects to prevent resource misallocation. Lastly, the Ministry of Foreign Affairs and the Defence Intelligence Agency were advised to strategically align foreign military aid with national development priorities, ensuring that such support strengthens both military capacity and socio-economic well-being. These measures were deemed essential for aligning Nigeria’s security expenditure with its broader human development goals.