This study examines the economic impacts of an infrastructure investment programme in Guinea‐Bissau for the period 2014–2030 using a dynamic computable general equilibrium model. Social accounting matrix (SAM) takes into account informal activities, and the model integrates funding schemes for infrastructure investment. We found that debt‐funded infrastructure investment will generate positive macro‐ and micro‐level externalities in terms of growth and well‐being outcomes across household groups in the urban and rural environments and contribute to inequality reduction. However, direct tax funding scheme is not the best economic development alternative for a country with a low per capita income.