The next king will be Prince Salman bin Abdulaziz, state television reported early Friday.
The announcement of his death comes several weeks after the state-run Saudi Press Agency said Abdullah was suffering from pneumonia and had been admitted to the hospital.
State television showed throngs of mourners gathered in Mecca.
King Abdullah became king of the oil-rich nation, a key U.S. ally in the Middle East, in August 2005. But he’d been running Saudi Arabia since 1996, following his half-brother King Fahd’s stroke.