The six-year-old victim, a French national who was on holiday with his parents, suffered life-changing injuries.
After his arrest, Bravery told police he had planned the attack to highlight his alleged mistreatment because of his autism.
As well as being autistic, Bravery has OCD and is likely to have a personality disorder, the court heard.
After the attack, he approached a member of staff and said: “I think I've murdered someone, I've just thrown someone off the balcony."
He is said to have carried out the attack in a bid to appear on the news, according to the BBC.
Bravery, from Ealing, West London, pleaded guilty to attempted murder at the Old Bailey and will be sentenced in February.
He was 17 at the time of the attack and could not be named until his 18th birthday in October.
The Met Police’s Det Chief Inspector: “This was an incredibly unusual and traumatic event and I can only imagine the horror the victim’s family felt as they realised what had happened to their child.
“The motive behind Jonty Bravery’s actions remains unclear. However, what is clear is the damage that has been done to this family, who have remained courageous and dignified in the face of such trauma, in addition to widespread media coverage of the incident.”
The child’s family said the young boy is still struggling with his mobility and cognitive function.
In a statement, they said: “Life stopped for us four months ago. We don’t know when, or even if, we will be able to return to work, or return to our home, which is not adapted for a wheelchair.
“We wish to thank all of the people, family and friends who have supported us throughout this horrific experience.”