Mr Aswat, 31, a British citizen, has been named by the British and US media as the alleged mastermind behind the blasts that killed 56 people including four suicide bombers.
However British police have not confirmed that he is wanted in connection with the attacks.
“Haroon Rashid Aswat … was arrested by metropolitan police officers following receipt of a US request for his extradition,” Scotland Yard said in a statement.
According to the BBC, Mr Aswat arrived at a Royal Air Force base in Northolt, west of London.
Mr Aswat was deported from Zambia on Sunday, leaving Lusaka international airport on a chartered plane to Britain.
US authorities have also reportedly sought to question Mr Aswat over alleged attempts to set up a terrorist training camp in Bly, Oregon.
US media said on July 22, the day after four abortive attacks on London’s transport system, that US police and intelligence agencies were taking part in the hunt for Mr Aswat.
They said that the four suicide bombers behind the July 7 attacks had made about 20 calls to him on his mobile telephone.
Mr Aswat, who spent time in South Africa and Botswana before entering Zambia on July 6, had been on a watch list of Western intelligence agencies who tipped off Zambian authorities.
Two more suspects were charged just hours later in London with perpetrating the four failed bombings in London on July 21.
Mokhtar Said Ibrahim, 27, suspected of trying to detonate a bomb on a Number 26 bus, and Ramzi Mohammed, suspected of trying to blow up an Underground train at Oval station, have been charged with attempted murder and conspiracy to murder, Scotland Yard said.
Yassin Hassan Omar, 24, was charged Saturday with attempted murder, conspiracy and possession of explosives over the attempt to bomb the Underground station at Warren Street in central London. They will appear in court today.
A fourth suspect, Hamdi Issac, has been held in Rome’s Regina Coeli prison since his arrest on July 29, several days after he fled Britain by train.
The 27-year-old Ethiopian-born Briton, who has a hearing scheduled for August 17, has been charged with “international terrorism” in connection with a failed attack on the Shepherd’s Bush Tube station.
Six others have been charged with the lesser crime of failing to reveal information to police, including three men in their early twenties.
A total of 39 arrests have been made in Britain in connection with the London attacks, with 16 still in custody in Britain plus Hamdi Issac, also known as Hussain Osman, who was arrested in Rome.
The government meanwhile declined to comment on newspaper reports that Saudi officials alerted Britain several weeks before the fatal July 7 suicide bombings that a terror attack was in the works.
Police have insisted that they had no prior warning of the July 7 attacks.
But the Observer newspaper quoted a security official in the Saudi capital Riyadh as saying information was passed to MI5 and MI6, Britain’s domestic and foreign intelligence agencies.
Britain’s Sunday Telegraph quoted the Saudi ambassador to Britain, Prince Turki al-Faisal, as saying: “There were reports passed on to your authorities several months ago (in April-May) in general terms of a heightened expectancy of attacks on London.”
Security sources played down the reports. The Observer quoted one source as “categorically” denying that any specific information had been received that could have averted the July 7 attacks.
The British Foreign Office declined to confirm or deny the claims. “We don’t comment on intelligence issues,” a spokesman said.