This article seeks to explain variations in presidential activism in semi-presidential countries in Sub-Saharan Africa. Africa is one of the continents where semi-presidentialism is most prevalent, but the dynamics of intra-executive relations are severely understudied. The four case studies discussed here—the Democratic Republic of Congo, Niger, Cabo Verde, and São Tomé e Príncipe—belong to the premier-presidential subtype. In this exploratory study, we aim to examine how institutional dimensions of premier-presidentialism interact with contextual factors to explain variations in presidential activism among Sub-Saharan African countries. In addition to fundamental contextual differences among the two pairs of countries, francophone and lusophone, there are specific institutional factors associated with the design and operation of premier-presidentialism that contribute to greater presidential activism in the two francophone cases. Taken together, these contextual and institutional factors skew effective executive power heavily toward the president in our francophone countries. We also find that the degree of political institutionalization matters for the impact of presidential activism on intra-executive conflict and government policymaking capacity. The article increases our understanding of the operation of semi-presidentialism in this understudied region, underscoring the importance of both contextual and constitutional factors for explaining variations in presidential activism in Africa.