Ashya King has left a hospital in Spain and is on his way to Prague to undergo proton treatment for his brain tumour.
The five-year-old left the Materno Infantil hospital in Malaga along with his parents Brett and Naghemeh King and headed to the airport where they are expected to board a private plane to the Czech Republic.
The Proton Therapy Centre in Prague gave to go-ahead for Ashya to receive treatment after examining documents from the hospital in Malaga where he has been receiving treatment after he was taken from Southampton Hospital on 28 August.
His parents were arrested in on suspicion of causing cruelty to a person under the age of 16 after they removed the child from the hospital and held in custody more than 300 miles away in Madrid.
The King's no longer face prosecution after the Crown Prosecution Service (CPS) withdrew the arrest warrant for them and the family were reunited soon afterwards.
The parents removed Ashya from Southampton Hospital without doctor's knowledge as the proton therapy treatment is not available via the NHS.
Ashya's grandmother, Patricia King, said how the family had "lost all hope" that the child would be the care his family wanted.
"We're overjoyed that he's finally getting treatment and we are so relieved," she added.
Kids'n'Cancer, a charity which raises money for children to have treatment, set up on online fundraising page to help fund the proton treatment.
Members of the public helped raised more than £30,000 for the family in 24 hours. The charity said a mystery donor also offered to pay the remaining fund for Ashya's proton beam therapy.