The mystery punter won the record-breaking £2,086,585 prize on an online fruit machine run by bookmakers Coral.
The payout is the biggest ever single jackpot by a UK punter.
The 49-year-old winner won a prize pot that had been rolling over for a year when he matched five symbols on the company's MegaJackpots Cluedo game.
The game is an online fruit machine, with the traditional symbols of cherries and bells being replaced by characters from the boardgame, such as Colonel Mustard or Miss Scarlett.
Players can stake between 2p and £5 a line.
The winning gambler, whose identity has not been released by Coral, is understood to have won the prize with a 50p spin.
He placed the bet on Wednesday, November 12, but the win has only just come to light.
It is understood the winning punter had only just opened an account with the bookmakers after taking up an offer to deposit £10 and receive £10 in free bets.
The game was linked to other similar online fruit machines around the world, and had a prize jackpot that grew and grew until a player scooped the jackpot.
Coral's spokesman David Stevens said: 'This jackpot game is played by people all over the world and the prize fund had built up to this record-breaking amount.
'We're delighted a coral.co.uk customer has scooped the lot. For one person at least, the credit crunch is no longer an issue.'
Do you know who the mystery punter is? Ring our newsdesk on 023 9262 2118.