At the eighth round of balloting among more than 1,000 lawmakers and regional delegates in the Chamber of Deputies, loud applause broke out when Mattarella passed the 505 votes needed for election.
Mattarella, 80, had ruled out remaining in office, but with the country's political stability at risk he changed his mind in the face of appeals from parliamentary leaders who met him at his palace earlier in the day.
In Italy's political system, the president is a powerful figure who gets to appoint prime ministers and is often called on to resolve political crises in the euro zone's third-largest economy, where governments survive around a year on average.
