Gareth Kendall, 32, correctly identified the ruins of Urquhart Castle in Scotland on the 20th anniversary edition of the TV quiz.
Delicatessen owner Gareth was amazed when asked where the castle ruins were located, replying: “I know this…because I lost my leg there”.
The audience gasped as Gareth explained he lost his left leg in a car smash near the Loch Ness-side castle while driving to Inverness.
He told yesterday how he is “keeping his options open” after scooping the cash, the highest amount won since the show rebooted with new host Jeremy Clarkson.
Speaking from his deli yesterday, Gareth said: “£125,000 is a lot of money so I am very pleased.
“I wanted to get to £16,000 because that would have been enough for me but I knew my general knowledge could get me further.
“I didn’t revise or swat up on questions – I just went for it.
“I’m keeping my options open on what to do with the money.”
Gareth previously said he would be forced to sell his Ken Deli store in Wyke, Bradford, West Yorkshire, following a spate of break-ins.
But he admitted he now wants to sell the business because he “doesn’t have enough time” to run it.
Gareth originally trained as a joiner before joining the Army aged 19. He served with the Royal Electrical and Mechanical Engineers but broke three vertebrae in his back in 2007 and was deemed unfit for tours of duty.
He remained with his regiment but was seriously injured in the 2012 car crash. As well as losing part of his left leg, Gareth sustained internal injuries and “died five times”.
He has “One Foot In The Grave” tattooed on the back of his right leg which points to his prosthetic limb.
The original version of Who Wants To Be A Millionaire? show ran from 1998 to 2014.