Shane Missler revealed his staggering lotto win in a Facebook status update posted half an hour after the draw on January 5, writing: "Oh. My. God.”

He immediately "retired” from his job at a background screening company, his lawyer confirmed, having won the fourth largest Mega Millions jackpot in history.

The overnight multi-millionaire, whose wealth now matches that of pop star Taylor Swift, said of his spending plans: "I’m only 20, but I hope to use it to pursue a variety of passions, help my family and do some good for humanity.”

He purchased the lucky ticket from a 7-Eleven newsagent in Port Richey, where his parents live, with the winnings from a scratchcard.

Mr Missler added he just had "a feeling” he might win and credited the power of positive thinking for the lotto outcome.

"If there is one thing I have learned thus far in my short time on Earth it is that those who maintain a positive mindset and stay true to themselves get rewarded,” he said.

"I intend to take care of my family, have some fun along the way and cement a path for financial success so that I can leave a legacy far into the future.”