The formalisation of informal security-providers has important consequences for citizenship, the rule of law, and human rights. We examine these policies in Burkina Faso, where formalisation has led to concerns about vigilante justice and ethnic targeting. Although African governments' reliance on informal security provision is well-documented, less is known about the origins of formalisation policies. To advance theory-building in this domain, this paper examines the political logic of empowering self-defence groups through the study of Burkina Faso's 2022 junta government, with comparisons to two prior regimes. We argue that formalisation is not only a mechanism for overcoming vexing security challenges, but is a tool used by leaders to build legitimacy and strengthen the regime's grip on power. In doing so, the article contributes insights into the origins of governmental policies towards self-defence groups, with implications for the study of political legitimacy, security provision and citizen–state relations.