Saudi state television has reported that King Abdullah has died aged 90.
His expected successor is his 79-year-old half-brother, Prince Salman, who recently has taken on the ailing king’s responsibilities.
The announcement came in statement read by a presenter on Saudi state TV, which aired video of worshippers at the Kaaba in Mecca.
King Abdullah was a powerful United States ally who joined Washington’s fight against al Qaida and sought to modernise the ultraconservative Muslim kingdom.
Before the news was broadcast Saudi television aired Koranic verses, which often signifies the death of a senior royal.
Abdullah had been King since 2005 but suffered from poor health in recent years, most recently he was in hospital suffering from a lung infection.