The woman, who wishes to remain anonymous, was playing William Hill Vegas online, when she scooped an accumulated jackpot that had been builing for around 18 months on the Festival of Lights game.
The woman, who is in her early forties and works in a school, said she didn’t know how she would spend her winnings - apart from booking a holiday to Disneyworld for her and her seven-year-old son.
She added: “I was washing the dishes this morning and thought to myself – ‘no matter how much money you have, you still have to wash the dishes.’
“It is all still so surreal. You obviously play these games, hoping to win a couple of quid, not a couple of million. I’m still stunned.”
The win is thought to be the biggest sum ever won by a William Hill customer.
A spokesperson added: “This, by our reckoning is the biggest sum that a William Hill customer has ever won. It is an incredible, life-changing sum of money.”
Incredibly, the woman bagged £30,000 with William Hill just three months ago.