Do experts rationalize and legitimize authoritarian governance? Although research on expert actors in contexts of democracy and international governance is now extensive, scholarly work on their role in authoritarian settings remains limited. This article helps open the black box of authoritarian decision-making by investigating expert advisers in the Arab Gulf monarchies, where ruling elites have enlisted them from top universities and global consulting firms. Qualitative fieldwork combined with three experiments casts doubt on both the rationalization and legitimacy hypotheses and also generates new insights surrounding unintended consequences. On rationalization, the evidence suggests that experts contribute to perverse cycles of overconfidence among authoritarian ruling elites, thereby enabling a belief in state-building shortcuts. On legitimacy, the experiments demonstrate a backfire effect, with experts reducing public support for reform. The author makes theoretical contributions by suggesting important and heretofore unrecognized conflicts and trade-offs across experts’ potential for rationalizing vis-à-vis legitimizing.