Kevin Shannon, 23, plans to spend the next three years cycling 36,000 miles across Europe, Asia, Australasia and the Americas.
He will also cross two oceans as a yacht crew member in a bid to complete his journey with zero emissions.
Kevin, from Mobberley, the same Cheshire village as mountaineer George Mallory, hopes to raise £1m for charity.
He will face testing conditions along the way as he experiences sub-zero temperatures, scorching heat, thirst, hunger, as well as physical and mental exhaustion and loneliness.
The expedition, in which he will cycle across the Gobi Desert in Mongolia, is so tough that Sir Ranulph Fiennes, the greatest living adventurer, and British explorer Benedict Allen have agreed to be patrons.
Kevin said: "It began as a simple gap year to be honest.
"But flicking through the brochures I decided I wanted to do something slightly different.
"I came across a book by someone who had cycled to Beijing and struck upon the idea of cycling to Sydney. Then I thought if I'm going that far, I might as well do the Americas on the way back.
"It has been a difficult year organising the trip, emailing sponsors, getting equipment and training for cycling, survival and sailing." Kevin, whose dad and friends have served in the forces, is raising money for Combat Stress, a charity that helps profoundly traumatised veterans.
"It's a very worthwhile cause," he said, "and I have friends who have been helped by the charity.
"It will keep me going when things get tough.
"I'm looking forward to the freedom and meeting interesting people along the way.
"My route is flexible, so if I hear of a village or mountain to visit, I'll go.
"It will be surreal setting out on the first day, with at least 25 kilos of kit and everything ahead of me. But I can't wait to get on the road."
Kevin, who recently finished a degree in digital animation in London, had planned to set off this week but he has postponed the trip for a few months because a documentary team has taken an interest in filming his journey.
Visit becauseitisthere.co.uk to sponsor Kevin.
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Mad Welsh Scotsman, Cadishead (03/09/2009 at 08:58)
That first sentence speaks volumes, lets hope a future headline does not read "Inexperienced adventurer (and TV crew) rescued during severe weather conditions". Too many people push themselves far beyond their known capabilities and have to rely on the humans instinct of survival often with dire consequences to them and resue parties.