The winning Superenalotto ticket - worth 146.9 million euros - was bought in a coffee bar in Bagnone, a Tuscan village of 2,000 people.
There had been no winner since January, leading to mounting lottery fever, with people from around Europe travelling to Italy to buy tickets.
Saturday's draw was 10, 11, 27, 45, 79, 88. A jackpot-winning combination had not emerged for 87 consecutive draws.
The BBC's Mark Duff in Italy says the economic crisis has added to the lottery's attraction, as many workers face grim prospects on their return home from the summer holiday.
Italian news agency Ansa said the unnamed winner had spent just two euros on the ticket.
Our correspondents says there is one other winner - the Italian treasury has kept about half the money gambled on the national lottery.