Baghdadi came to prominence in 2014, when he announced the creation of a “caliphate” in areas of Iraq and Syria.
IS carried out multiple atrocities that resulted in thousands of deaths.
The jihadist group imposed a brutal rule in the areas under its control and was behind many attacks around the world. Although the US declared the “caliphate” defeated earlier this year, IS militants remain active in the region and elsewhere.
Baghdadi’s death is a major victory for Mr Trump as he faces heavy criticism for his decision to pull US troops out of northern Syria and fights an impeachment inquiry launched by Democrats.
In an unusual Sunday morning statement, Mr Trump said Baghdadi ran into a dead-end tunnel in Idlib province, “whimpering, crying and screaming”, while being chased by military dogs.
“The thug who tried so hard to intimidate others spent his last moments in utter fear, in total panic and dread, terrified of the American forces bearing down on him,” he said.
Baghdadi, who was with three children, killed himself and all of them by detonating his vest, Mr Trump said. The blast mutilated Baghdadi’s body but, according to the president, an on-site DNA test confirmed his identity.
No US personnel were killed, he said, but one of the dogs was injured.
What is known about the operation?
The location near the Turkish border was far from where Baghdadi had been thought to be hiding along the Syria-Iraq border. Many parts of Idlib are under the control of jihadists opposed to IS but rival groups are suspected of sheltering IS members.
Baghdadi had been under surveillance for “a couple of weeks” and “two or three” raids had been cancelled because of his movements, Mr Trump said, describing the IS leader’s move to Idlib as part of a plan to rebuild the group.
The forces targeted the compound using eight helicopters, which were met with gunfire, Mr Trump said. The commandos entered the building by blowing holes in the wall, avoiding the main door which was booby-trapped.
When Baghdadi detonated his vest, the president said, the tunnel caved on him. “He was a sick and depraved man, and now he’s gone… He died like a dog, he died like a coward.”
A number of Baghdadi’s followers also died while others were captured, the president said. The special forces spent two hours in the area, and gathered “highly sensitive material”.
Mr Trump said he watched Saturday’s operation from the Situation Room, and the White House released a picture of him surrounded by Vice-President Mike Pence and top security officials.
Syrian Kurdish-led forces – one of the main US allies in northern Syria until Mr Trump withdrew US troops from the area earlier this month – said they had carried out a “historic” joint operation while the Iraqi military said it had provided “accurate information” about Baghdadi’s location.
Mr Trump praised them, as well as Russia – which opened up the airspace it controls for the operation – Turkey and Syria for giving “certain support” to the operation.
On Twitter, UK Prime Minister Boris Johnson said Baghdadi’s death was “an important moment in our fight against terror but the battle against the evil of [IS] is not over yet”.
While IS lost its territory in Syria and Iraq after a years-long deadly campaign, experts say the group remains a threat, with affiliates active in various countries.
A foreign policy success for Donald Trump
The strategic significance of Abu Bakr al-Baghdadi’s death is clear. Removing a skilled and brutal leader from the battlefield will undoubtedly make allied efforts to eradicate IS forces easier. The lasting political benefits for Donald Trump remain to be seen.
Baghdadi was far from a household name in the US, although IS has been a well-known adversary ever since its brutal executions and advance grabbed headlines in 2014. His death will give Mr Trump a signature moment to cite when making the case that his leadership has led to the methodical defeat of IS forces.
It also will help deflect from weeks of sharp bipartisan criticism following the president’s decision to remove US forces from northern Syria and tacitly permit a Turkish invasion to drive out US-allied Kurds.
While it is true most Americans only pay attention to foreign policy during times of war, most of Mr Trump’s current political headaches have come from actions directed abroad – whether it’s the Syrian move or the rapidly unfolding impeachment inquiry into his Ukraine conduct.
Now the president has a clear foreign policy success to tout. It will not solve all his political problems, but it is a start.
Who was Abu Bakr al-Baghdadi?
Baghdadi, whose real name was Ibrahim Awwad Ibrahim al-Badri, had a reputation as a highly organised and ruthless battlefield tactician. He was described as the world’s most wanted man.
He was born near Samarra, north of Baghdad, in 1971, and reports suggest he was a cleric in a mosque in the city around the time of the US-led invasion in 2003.
Some believe he was already a jihadist during the rule of former Iraqi leader Saddam Hussein. Others suggest he was radicalised during the time he was held at Camp Bucca, a US facility in southern Iraq where many al-Qaeda commanders were detained.
Baghdadi emerged in 2010 as the leader of an umbrella group that included al-Qaeda in Iraq, and rose to prominence when IS militants captured the Iraqi city of Mosul in 2014, when he declared the creation of a “caliphate”.
That was the only time Baghdadi was seen in public. At its peak, IS had eight million people in territories under its control. Baghdadi only reappeared in a video released by IS earlier this year.
In October 2011, the US officially designated him a “terrorist” and offered a reward of $10m (£5.8m at the time) for information leading to his capture or death. This was increased to $25m in 2017.