Riyadh: King Abdullah died early Friday of complications from pneumonia and has been succeeded by his brother Salman, the Saudi Arabian royal household said in a statement.
"His Highness Salman bin Abdulaziz Al Saud and all members of the family and the nation mourn the Custodian of the Two Holy Mosques King Abdullah bin Abdulaziz, who passed away at exactly 1 a.m. this morning," the statement said.
The monarch was hospitalised Dec 31 for medical tests.
Abdullah bin Abdulaziz was born in 1924 and became king in August 2005 following the death of his brother King Fahd.
Abdullah underwent back operations in 2010, 2011 and 2012.
Born in 1935, Salman became Saudi crown prince in June 2012 and served under Abdullah as deputy prime minister and defence minister.
One of Salman's first acts as king was to proclaim his brother Muqrin as crown prince.
Abdullah signed a decree last March designating Muqrin as second-in-line to the throne.
Abdullah, Salman and Muqrin are sons of the Saudi kingdom's founding monarch, Abdulaziz, more commonly known as Ibn Saud, who died in 1953.