White Muslim convert Richard Dart, 30, a former security guard for the BBC, was sentenced to six years' imprisonment at England's Old Bailey central criminal court in London.
Imran Mahmood, 22, was jailed for nine years and nine months and 26-year-old Jahangir Alom for four-and-a-half years.
Dart and Alom had admitted seeking terror training in Pakistan while Mahmood, who had already received terror training, gave them advice.
Judge Peregrine Simon told the trio they had "radical beliefs and have shown yourselves to be committed to acts of terrorism".
Dart refused to stand as he was sentenced, saying: "I believe ruling and judging is only for Allah."
The court heard that Dart and Mahmood discussed bomb-making and identified the southern English town of Royal Wootton Bassett – where British soldiers killed in Afghanistan were repatriated until 2011 – as a potential target.
"These are dangerous men," Stuart Osborne of Scotland Yard's Counter Terrorism Command said in a statement after sentencing.
"Mahmood had received terrorist training in Pakistan and suggested he had knowledge of how to make homemade explosives while Dart and Alom made great efforts to travel to Pakistan and aspired to seek training from terrorist groups there."
The three men were arrested in July last year.
All of them had been stopped at airports at various points while travelling to and from Pakistan.
Traces of explosives were found on two of Mahmood's rucksacks when he was stopped at Manchester Airport in northwest England in 2010.
Dart once featured in a documentary about his conversion to Islam and had changed his name to Salahuddin al-Britani.
The court heard that he and Mahmood communicated by typing into a document on Dart's laptop, in "silent conversations" designed to avoid surveillance.
They mistakenly believed that if they deleted the text it would not be stored on the computer, but forensic experts were able to retrieve the conversations.
Dart and Mahmood were both given extended sentences, meaning they will serve a minimum of two-thirds of their sentences.
Alom was a Police Community Support Officer and had also been in the Territorial Army volunteer reservists before he rejected mainstream society.
Dart, the son of teachers, was born in Dorset in southwest England. Mahmood was also born in Britain while Alom, a British citizen, was born in Bangladesh.
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In the past one month the acts of Terror by a certain community in places where it is in minority. 1) Bangalore blasts, 2) Boston Marathon.
Its not just in Britain, but anywhere there there are sufficient number, the incidences occur. We have seen attacks in China, Russia, Spain,etc.
@Arsalan
Really? The rest of the world has already reached a point of no return regarding Islam. Look at the backlash that is happening in Sri Lanka, Thailand, Burma, Europe..The world is slowly, but surely waking up my friend.
They should lock them up and throw away the key.
Interesting! You are a normal human being. You are a guard whose aim is to protect. Then you convert. Then you think of blowing up people!
Coudn't they award more lenient punishments? Nine and a half year's too long for planning terrorist attacks!
The bad news for Islam keeps on piling up. Is this their way of serving the religion? Do they know what kind of damage they are doing?