This article examines how successful Putin and Trump’s personality cults were in consolidating authoritarianism in their respective regimes, Russia and the US, during periods of democratic erosion, known as democratic backsliding. My research investigates how both leaders’ authoritarian consolidation is dependent on their regime type and conditions. This is because the existing institutions and political frameworks of a regime either adopt or reject their personality cults, enabling or limiting the success of their authoritarian consolidation. Also, the success of each cult’s authoritarian consolidation is dependent on the leaders’ abilities to navigate and respond to opposition and conflict, which determines their cult disintegration or survival. My research builds a contemporary theoretical framework of modern personality cults and uses a comparative case study to analyse Putin and Trump’s consolidations of authoritarianism through personality cult institutionalisation and democratic backsliding. My results demonstrate that Putin’s cult has successfully consolidated authoritarianism in Russia by using the regime’s existing frameworks to advance his personality cult and pre-emptively limit oppositional activity. In contrast, during his presidency, Trump’s cult did not successfully consolidate authoritarianism in the US, because his cult was consistently undermined by the existing democratic institutions and hindered by both internal and external political contestation.