Reuters reporters saw the chartered plane believed to be carrying Duterte land at Rotterdam airport on Wednesday. The source confirmed that the 79-year-old was onboard. An ambulance was seen pulling up near the plane.
At the ICC in The Hague, Duterte will face allegations of crimes against humanity for overseeing death squads in his war on drugs. He could become the first Asian former head of state to go on trial there.
Duterte was set to be transferred to a detention unit on the Dutch coast and will be brought before a judge within days for his initial court appearance.
Duterte, who led the Philippines from 2016 to 2022, was arrested early on Tuesday in Manila, marking the biggest step yet in the ICC's probe into an anti-drugs crackdown that killed thousands and drew condemnation around the world.
The plane had originally been set to land in the Netherlands early on Wednesday morning, but was delayed after a long layover in Dubai during which Duterte received medical checks.
The ICC's warrant for his arrest says that as president, Duterte created, funded and armed death squads that carried out murders of purported drug users and dealers.
About 20 anti-Duterte protesters gathered earlier outside the ICC in The Hague with banners, including one that said: "We demand justice and accountability, Rodrigo Duterte is a war criminal!". A protester held a big cardboard mask depicting Duterte as a vampire.
"This is great news for Filipino people," anti-Duterte protester Menandro Abanes said of Duterte's arrest and expected transfer to the international court.
"I'm here to show my appreciation to (the) ICC for doing its job to end impunity."
Another protester, Mary-Grace Labasan, said: "Actually, he is lucky, because he is experiencing the due process of law compared to the victims who were just being shot and killed without any due process."
A handful of pro-Duterte protesters also gathered at the court building.
"They handed our president to foreigners," protester Janet Suliman said.
"They brought shame to our (country)."
Back home, for families of Philippine drug war victims, Duterte's arrest has revived hopes for justice.
The war on drugs was the signature campaign platform that swept the mercurial Duterte to power in 2016. During his six years in office, 6200 suspects were killed during anti-drug operations, by the police's count.
Activists say the real toll was far greater, with many thousands more slum drug users, some of whom were on community "watch lists" after they signed up for treatment, gunned down in mysterious circumstances.
Lawyers and academics said the arrest and transfer were "a big moment" for the ICC, which is targeted by US sanctions and does not have any police of its own to arrest people.
"This is an opportunity for the court to show that it can deal with a big case and can have arrests," said Iva Vukusic, an assistant professor of international history at Utrecht University.
The former president's daughter Sara Duterte, the country's vice president, boarded a morning flight to Amsterdam, her office said, but it did not say what she intended to do there or how long she planned to stay in the Netherlands.
Silvestre Bello, a former labour minister and one of the former president's lawyers, said a legal team would meet to assess options and seek clarity on where Duterte would be taken and whether they would be granted access to him.
Duterte's youngest daughter, Veronica, plans to file a request with the Philippine Supreme Court to compel the government to bring him back, Salvador Panelo, his former chief legal counsel, said.
