This chapter analyses the evolving relationship between Islamism and state power in Saudi Arabia, focusing on the securitisation of Islamist movements and the central role of Wahhabism in legitimising monarchical authority. It traces the strategic alliance between the Al Saud monarchy and the Wahhabi religious establishment, exploring how this relationship has both enabled and constrained the state’s political control. While Saudi Arabia has promoted Wahhabi Islam internationally, it has simultaneously suppressed domestic Islamist movements viewed as threats to regime stability, from the 1979 Grand Mosque seizure to the rise of the Sahwa movement and post-9/11 militancy. The chapter investigates how the Saudi state has framed both violent and non-violent Islamist actors as security threats to justify repression and consolidate control. Under Crown Prince Mohammed bin Salman, securitisation has intensified alongside economic reforms and the rebranding of Saudi Arabia’s global image. Ultimately, the chapter argues that the kingdom’s response to Islamism reveals a deliberate strategy to control religious discourse, neutralise dissent and reinforce authoritarian rule.