Khalid Ali,28, was arrested in Parliament Square last April by armed police who found him in possession of three knives.
Police had been watching Ali since he returned from Afghanistan where he had spent five years making bombs for the Taliban which were used to maim and kill coalition troops.
The FBI in late 2016 matched his fingerprints to those of two caches of explosives recovered in 2012.
After being tried at the Old Bailey in June, he was convicted of preparing terrorist acts in Britain and two charges of possessing explosive substances with intent abroad.
Sentencing, Judge Nicholas Hilliard QC handed Ali three life sentences.
He gave a minimum of 40 years for making IEDs for the Taliban in 2012 and 25 years for the plot to kill in Britain and attract “maximum publicity and instil terror”.
The judge said: “I am absolutely sure you were in Afghanistan. You were a valued member of a team making IEDs that were detonated in combat between January and July 2012.”
“I have no doubt whatsoever that there is a very considerable risk of your committing offences of violence in the future and cause death or serious injury as a result.
“I’m sure your plan was to attack and kill someone in central London.
“Your preparations were complete and you very simply had to identify your precise target and his or her death was very likely to be caused by a knife attack. You would kill any police officer you could.”