This paper examines the delegitimation of the Other in selected messages of Boko Haram (BH), using seven of the messages delivered by the longest-serving BH leader, Abubakar Shekau. The messages delivered during Shekau’s period as the BH leader between 2009 and 2021, were identified using f4analyse as a coding tool and discussed analytically using Theo van Leeuwen’s Discourse Legitimation approach to discourse analysis. The analysis unearths Shekau’s deployment of four delegitimation strategies: authorisation, moralisation, rationalisation and mythopoesis to discredit the actions and practices of the Other–those who do not associate with BH. The four delegitimation strategies are linguistically realised through negative other-presentation strategy. The messages deployed polarisation, other-condemnation, other-blaming, negative tagging (derogatory labelling/nomination) of anti-BH, other-exclusivity in perceived positive contexts, metaphorising, hyperbolising and euphemising to accentuate in-group consensus and in-group solidarity. The strategies are deployed to negatively represent the Other in order to delegitimise their actions, beliefs and principles.