The teenager who planted the Parsons Green Tube bomb which injured 51 passengers will be sentenced later.
Iraqi asylum seeker Ahmed Hassan, 18, pretended to engage with the anti-terrorism Prevent scheme as he plotted to cause carnage in the capital.
He made a bomb with 400g of “Mother of Satan” explosives and 2.2kg of shrapnel while his unsuspecting foster parents were on holiday in Blackpool.
The Old Bailey heard he wanted to avenge the death of his father in Iraq and was “disappointed” when the bomb only partly detonated in a huge fireball.
A jury deliberated for just over four hours to reject his explanation that he only wanted to act out a fantasy like the Tom Cruise film Mission: Impossible.
The photography student, who claimed to aspire to be the new David Attenborough, will be sentenced for attempted murder by Mr Justice Haddon-Cave later.
Following his arrival in Britain in 2015, Hassan told Home Office officials he had been trained to kill by Islamic State.
The court had heard he was referred by Barnardo’s and Surrey social services to Prevent but kept his murderous plans a secret.
Hassan used his student of the year award of a £20 Amazon voucher to buy one of the key chemicals online.
The night before the bombing, his foster father Ron Jones went to find out why Hassan was not sleeping, unaware he was sitting next to the highly unstable TATP explosives.
On the morning of September 15 last year, Hassan left his home and caught a train to Wimbledon carrying his bomb inside a Lidl bag.
He set the timer in Wimbledon then got off the train one stop before the bomb partially exploded on the floor of the carriage at Parsons Green.
Twenty-three passengers suffered burns, with some describing their hair catching fire and their clothes melting in the blast.
And 28 more suffered cracked ribs and other crush injuries in the stampede to get out of the platform via a narrow stairway.
Meanwhile, Hassan destroyed his phone and changed into a Chelsea shirt as he fled London with more than £2,000 in cash but was picked up by police at the Port of Dover the next day.
Hassan’s foster parents Penny and Ron Jones, who were awarded an MBE in 2010, did not give evidence in the trial.
Afterwards they said authorities should have warned them to look out for signs of radicalisation.
Mrs Jones told ITV News: “I am cross with him for what he’s done, and that he’s done this in my house makes me feel very, very betrayed, I can’t help that. Because he’s such a bright and intelligent child, he’d got a good future ahead of him.”
Commander Dean Haydon, head of Scotland Yard’s Counter Terrorism Command, said he was “intelligent and articulate” but also “devious and cunning in equal measures”.
He said: “On the one hand he was appearing to engage with the (Prevent) programme but he kept secret what he was planning and plotting.”
Mr Haydon said it was “good fortune” the bomb did not fully detonate and kill and injure many passengers.
A review of Hassan’s dealings with Prevent is under way.