He died on Friday "at 1:00 am (2200 GMT)" and would be buried later in the day following afternoon prayers, said the statement.
In recent years, his advanced age and poor health had raised concerns about the future leadership of one of the world's key oil producers.
Abdullah's half-brother Salman, 79, was named crown prince in June 2012 following the death of Prince Nayef bin Abdulaziz. Salman had been representing the king at most recent public events because of the monarch's poor health.
In March 2014, King Abdullah named his half-brother Prince Moqren as a second crown prince, in an unprecedented move aimed at smoothing succession hurdles. Moqren, who was born in 1945, is the youngest of Abdulaziz's sons.
Since the death in 1952 of King Abdulaziz al-Saud, the founder of Saudi Arabia, the throne has systematically passed from one of his sons to another. But many of them are old or have died.
King Abdullah Ibn Abdulaziz Al-Saud of Saudi Arabia presided over his oil-rich, deeply religious and often divided nation at a time of unprecedented upheaval in the Arab and Muslim worlds.
When he succeeded to the throne, and the equally important office of Custodian of the Two Holy Mosques, he had already been de facto ruler for 10 years. His half-brother King Fahd, whom he eventually succeeded, had suffered a debilitating stroke after years of well-documented high living.
As Crown Prince, Abdullah therefore had to deal with the fallout from the 9/11 attacks on America, for which his subjects were largely responsible as both perpetrators and inspiration.
His distrust of America and the West set him apart from Fahd and other predecessors; but those differences also laid the path for a man who had won high political regard in his youth as a conservative to establish a distinctive, and decidedly more liberal, approach to governance as monarch.
He tried to liberalise the country's economy, and became known as something of an advocate for women (within Saudi Arabia's harsh traditional constraints), promoting female education, and appointing a woman minister, and even 30 women to the Shura, the national advisory council.
Britain's Queen Elizabeth II, left, stands next to King Abdullah of Saudi Arabia and Prince Charles. Photo / AP
Any plans for faster reform, though, were scuppered by the "Arab Spring". The combination of pro-democracy activism in the Arab world, supported by Saudi Arabia's traditional western allies, and the rise of the Muslim Brotherhood, was the Sauds' worst nightmare come true.
Within months, King Abdullah had signed off on a reversion to traditional authoritarianism, jailing human rights workers, lawyers and promoters of political Islam, and refusing to give ground on the increasingly symbolic issue of the ban on women drivers.
He clashed with US President Barack Obama over the latter's reaching out to Saudi Arabia's regional rival Iran, and moved decisively to topple Egypt's first democratically elected president, the Brotherhood's Mohammed Morsi, backing General Abdulfattah al-Sisi's military coup in 2013.
Abdullah's life
Abdullah Ibn Abdulaziz al-Saud was born in 1923, the 13th of more than 35 sons of Abdul Aziz Ibn Saud, the founder of modern Saudi Arabia. He received a court education in religion, chivalry and politics, being tutored in Koranic schools and by the ulemas (religious teachers), but supplemented this with his own reading in many different fields. He became known as more personally religious than some men in the family, who pursued greater pleasures abroad than they allowed at home, but was never at the extreme end of the country's severely Wahhabi religious establishment.
His merits and future leadership role were recognised in 1962, when the then Crown Prince Faisal appointed him head of the National Guard, while naming his half-brother and rival Prince Sultan as minister of defence. Sultan and Fahd were leading members of the so-called Sudairi Seven full brothers, and the balancing act initiated then, between the personally conservative but politically reformist Prince Abdullah, and the politically conservative and pro-American Sudairis, came to dominate Saudi politics over successive decades.
Sultan became Crown Prince to Abdullah on his accession, and although he died in 2011, both the current Crown Prince, Salman, and the next in line after him, Prince Muqrin, are also Sudairis.
Prince Abdullah emerged as an important public voice for the Saud family in 1969, calling for the execution of air force officers who had mounted an abortive coup. His opposition to the westernising proclivities of Fahd and Sultan was pronounced from that time. He also condoned the execution of Princess Mishail, the royal adulteress whose story was featured in the British television documentary Death of a Princess.
Meanwhile, he sought to consolidate his power base by modernising the National Guard, an internal security force recruited from a network of tribal settlements to form a countrywide force of Bedouin. It became known as the White Army, because its members wore their own thobes (flowing garments) instead of khaki uniforms. Under his leadership the National Guard bought a complete telecommunications system of its own and placed valuable contracts with Cable & Wireless, as well as building a private cradle-to-grave health service for its members and their families.
King Abdullah. Photo / AP
Prince Abdullah was named second deputy prime minister after King Khalid succeeded to the monarchy on the assassination of King Faisal in 1975. He broadened his outlook with visits to the United States, Britain, Spain and France, but unlike other members of the royal family he was never comfortable in the West, preferring the company of Bedouin tribesmen. Like most Saudi royals he was a keen falconer.
The 1979 uprising by religious fanatics, resulting in a bloody siege at the Grand Mosque in Mecca, propelled Prince Abdullah into the limelight. The incident emphasised the vulnerability of the pro-Western modernisers led by Fahd, then Crown Prince, to the charge that they had neglected Islamic values.
After 1980 Prince Abdullah's picture was spread across newspapers and public buildings, and his long-time opposition to rapid modernisation and closer relations with the US was seemingly vindicated by the collapse of oil prices in the early 1980s which plunged Saudi Arabia into recession.
During the Iran-Iraq war of the 1980s Prince Abdullah was sent in search of new allies for the Saudis, who felt increasingly vulnerable after the Islamic revolution in Iran. Prince Abdullah's mother belonged to an important family of the Shammar tribe, whose lands and relationships extend into Syria and Iraq. He became a useful tool for Saudi diplomacy with hard-line Arab states, especially Syria, where he enjoyed the confidence of President Hafiz Assad.
That relationship was reflected in his repeated attempts to come to terms with President Assad's son and successor Bashar - attempts which ended with a breakdown in relations so extreme that the Saudis took the lead in trying to engineer his overthrow in the ongoing civil war.
As Crown Prince, his conservatism and reputation as a man of principle put him in a much stronger position than either of his predecessors, Kings Khalid and Fahd, to embark on a process of cautious political reform, aimed at moving Saudi Arabia away from traditional religious-tribal loyalties and faith-based obscurantism into the modern age.
He became the first senior Saudi figure to speak publicly of reform and democracy, and to acknowledge the existence of minorities, notably the Shia, in the kingdom. He initiated the kingdom's first elections which, though limited to local government and excluding women, struck a chord with most Saudis. He was also credited with the purging of more than 3,000 extremist preachers from mosques and Koranic schools, the creation of a human rights commission, and the hosting of a series of public debates on women's rights.
US President George W. Bush greets Saudi Crown Prince Abdullah in 2005. Photo / AP
As King, Abdullah won respect for his drive to stamp out graft. He continued on the path of cautious reform, which he balanced with a respect for Saudi tradition. He pushed changes aimed at creating jobs by liberalising markets and loosening the grip of religious hardliners over education and social policy, in particular encouraging provision for female education, especially at university level.
In 2009 he fired the hard-line Sheikh Saad Bin Naser al-Shethri from the country's high council of religious scholars after the cleric had criticised his decision to allow male and female researchers to work together at the new King Abdullah University of Science and Technology, built outside Jeddah, which Abdullah saw as a key part of Saudi Arabia's drive towards economic modernisation. In 2012 he replaced the head of Saudi Arabia's religious police, the "mutawa", with a new man widely seen as more moderate than his predecessor.
He also promised Saudi women the vote and the right to stand in future elections to municipal councils, the highest elected bodies in the country; and in 2013 he appointed 30 women to the consultative 150-member Shura Council. Critics, however, dismissed the move as little more than a symbolic gesture, in that local and municipal elections, and the Shura Council, have an extremely limited effect on national political decision-making. Neither did the king accede to demands that women be given the right to drive - a move that might have allowed them to campaign in their putative constituencies.
Foreign affairs
In foreign affairs, Abdullah's reign was widely noted for deteriorating relations with Saudi Arabia's key western ally, the United States, after the election of Barack Obama. In reality, Saudi Arabia's anger over America's abandonment of Hosni Mubarak in Egypt, its perceived support for the Muslim Brotherhood, and the reaching out to Iran rather than confrontation over Tehran's nuclear programme, was an extension of the king's already established dislike of how Washington conducted policy. He is known to have felt betrayed by the failure of President George W Bush to pursue a resolution to the Palestinian question, and Saudi Arabia did not support the invasion of Iraq in 2003.
Pope Benedict XVI welcomes King Abdullah at the Vatican. Photo / AP
He was certainly not prepared to allow American idealistic sentiment to cloud his judgment in his own back yard, sending Saudi tanks into Bahrain to put down pro-democracy uprisings led by that country's Shia majority in March 2011, and ruthlessly wiping out a growing domestic civil rights movement as the contagion of Arab protest spread. He reverted to the traditional method of governmental largesse to dissuade the Saudi people from pursuing their own "Spring".
Saudi Arabia's careful pursuit of its own goals while maintaining the all-important military alliance with America reached its apogee with its support for carefully chosen rebel groups in Syria that would conform to Washington's demands when it came to fighting al-Qaeda and its offshoots while remaining loyal to Riyadh's vision of itself as undisputed leader of the Sunni Muslim world.
The deepest cause of US-Saudi discord was the American administration's growing rapprochement with Iran, whose nuclear ambitions Abdullah regarded as a mortal threat to Saudi Arabia. A leaked diplomatic cable from 2008 disclosed his pithy advice to America, demanding that it "cut off the head of the snake". Instead, Obama chose to talk to the serpent; worse, he reached a deal in November 2013 when, after months of secret diplomacy, Iran agreed to observe temporary limits on its nuclear programme.
Shrinking circle of ageing princes
Commentators detected two significant factors behind the cooling of relations, which also remain the greatest challenges to Saudi Arabia's stability and future prospects of gradual reform. The Saudi economy has failed to diversify from its dependence on hydrocarbons, while a growing percentage of oil production is consumed by domestic energy needs. At the same time America's domestic energy boom is steadily reducing its dependence on Saudi oil, a fact which may or may not have been a factor in Saudi Arabia's apparently self-defeating recent decision to precipitate a collapse in the price of oil.
King Abdullah. Photo / AP
Then, there is no doubt that Saudi Arabia's standing in the world in general, and the West in particular, has been weakened by the perception that it is ruled by a shrinking circle of ageing princes, resistant to the modern world and the true needs of its people.
That image is partly unfair - the kingdom remains far more politically and socially diverse than the outside world is allowed to see. But the Saudi throne continues to be passed between the sons of Abdul Aziz ibn Saud, as it has been since his death in 1953, the youngest of whom, Prince Muqrin, 69, is now in line to become Crown Prince . Abdullah's chosen successor, Crown Prince Salman, is unwell and is likely to reign in name only. Many of the vast generation of Ibn Saud's grandsons waiting in the wings are now grandfathers themselves, and no transparent mechanism has emerged to divine who might be the first of that generation to succeed.
King Abdullah was said to have had more than 30 wives, though not all at the same time - so many that during one religious festival he rented an entire hotel at Taif for a grand reunion of his children and former wives. He had at least 15 sons and 20 daughters.
A book of photographs published by the king's son-in-law Prince Faisal portrayed a rather homely man variously swigging from a can of Diet 7-Up, teasing his youngest children, wearing a colourful Hawaiian shirt, scrabbling for truffles in the desert with a long-handled trowel and playing boules (which he was always allowed to win).
Saudi King Salman
Saudi King Salman. Photo / AP
Saudi King Salman, who succeeded his half-brother Abdullah on his death, is a 79-year-old stalwart of the royal family credited with transforming the capital Riyadh during his half-century as governor.
Like Abdullah, Salman is seen as a moderate with a reputation for austerity, hard work and discipline, especially in his role overseeing the hundreds of young princes in the royal family.
Recent years have seen concerns over his health after operations on his back, but Salman took on an increasingly high-profile role as Abdullah's own health issues forced him from the limelight.
Born on December 31, 1935, Salman is the 25th son of the desert kingdom's founder Abdulaziz bin Saud and a prominent member of a formidable bloc of brothers known as the Sudairi seven, after their mother Hassa bin Ahmed al-Sudairi.
He is the sixth son of Abdulaziz to become king of the arid, oil-rich nation.
Salman was appointed governor of Riyadh province at the age of only 20, in line with a tradition of putting royal family members in charge of key provinces.
He is considered the architect of the development of Riyadh from a desert backwater to a modern metropolis, balancing the historic power of the Red Sea city of Jeddah.
The governorship "allowed him to serve as a generally very well respected arbiter of al-Saud family affairs, as well as overseeing the city's emergence," said Eleanor Gillespie of the London-based Gulf States Newsletter.
"Salman has a reputation for probity and for being 'clean' when it comes to money," Gillespie said.
Salman only took on his first ministerial post -- as defence minister -- in 2011 following the death of his brother Prince Sultan.
He was officially named crown prince following the death of the previous heir apparent, Nayef, in June 2012 and undertook a series of visits to Western and Asian nations.
He has since developed solid ties with foreign partners and "is probably Western policy-makers' favourite choice when it comes to future kings", Gillespie said.
Said to be a hard worker who arrives in the office every day at 7:00 am sharp, Salman also has a reputation for accessibility, holding court three times a week.
"He is a man of dialogue who always preferred to solve problems amicably," said Anwar Eshki, the director of the Jeddah-based Middle East Institute for Strategic Studies.
"He prefers moderation" in internal and foreign policy and "follows in the steps of Abdullah", who was a keen reformer, said Eshki.
Salman is also in charge of the many young princes in the royal family, who "respect and fear him", Eshki said.
- additional reporting by AFP