The question of how involvement in institutional politics and governance affects rebel groups’ behaviour is pertinent when studying violent non-state actors, both during and in the aftermath of conflict. This is especially the case when participation in the political system becomes sustained over time. The interactions between the political and governance practices of a rebel group and its overall ideological orientation and state-building aspirations are not sufficiently analysed in the literature, especially in the context of hybrid armed-political organizations operating in latent, frozen or protracted conflicts. This article aims to begin to fill this gap by examining how involvement in institutional politics has shaped both Hamas’s and Hezbollah’s branding, interpretation and reliance on their own constitutive ideological manifestos, with an emphasis on both organizations’ dynamic processes aimed at reconciling political participation with their previous ideological rejection of the legitimacy of the political system and their constitutive calls to dramatically restructure the political order. Based on these detailed accounts, this article reflects on how the complex relationship between politics, electoral competition, governance and ideological principles can shape an armed group’s political identity.