This paper discusses the wider significance of Turkey’s recent transition to authoritarianism with respect to Islamist political theses' emergent affinity with the religious populist governance models. As Erdogan regime has continued to enjoy wide support of both erstwhile and current Islamists, this paper will probe whether this embrace represents a corresponding shift in the trajectory of Muslim governance models. Through an analysis of Turkey’s democratic breakdown, it lays out a narrative of gradual build-up of autocracy beginning with the earliest days of Erdoğan’s tenure. Given the success record of Erdoğan’s global bid for Muslim leadership, it inquires whether Turkey has come to serve as an authoritarian model of religious populism at the expense of the idea of an Islamic democracy for the Muslim-majority world. Resisting the ideological analyses that reduce Turkey’s de-democratization to AKP’s so-called Islamist ideology, the paper argues that Erdoğan’s bid for Muslim leadership and patronage of Islamists may still leave more lasting effects on Islamism’s trajectory and its relationship with democracy. Islamists’ preference for strong religious populist leaders in contradistinction with their longstanding declared principles of Islamic good governance may have illustrated the use of democratic means to create a decisively authoritarian state instead of providing a democratic model for the Muslim world, as Turkey under the AKP was once promoted. The paper will further engage with the normative literature on Islamic good governance to address whether the Turkish case has revealed not just the practical limitations of the theory, but also the shortcomings of the theoretical construct itself: have theories of Islamic democracy carried the underpinnings of a decidedly authoritarian regime that seamlessly aligned with Muslim populist regimes under conservative or ex-Islamist politicians, even while they failed to build their own Islamic states?