Public debt plays a major role in financing projects that support economic growth and sustainable development. As governments may choose between domestic and external borrowing, a comprehensive assessment of their effects would support this choice. Our study provides an integrative view of economic and social outcomes and compares, through externalities, the impacts of external and domestic public debt as methods of financing development, with a focus on the Cameroonian economy. Utilizing a dynamic computable general equilibrium (CGE) model and a microsimulation analysis, we find that domestic debt has more advantages for Cameroon compared to external debt, as it increases the large-scale economic impact by improving household welfare, boosting GDP growth, and progressively reducing poverty and inequality. It is therefore recommended that the Cameroonian government focus on increasing the use of domestic debt as a method of financing development by implementing policies that support domestic saving and promote the development of domestic debt markets.