SANTIAGO, Chile - Billionaire and former President Sebastian Pinera appeared headed to a victory in Chile's presidential runoff election, with more than 82 per cent of the votes counted Sunday night.

Officials said Pinera had just over 54 per cent of the votes to nearly 45 per cent for centre-left Sen. Alejandro Guillier.

Analysts had predicted a closer race, but there had not been any opinion polls on the election for several weeks.

The early results prompted Pinera supporters to celebrate at his campaign headquarters.

Pinera won last month's first round, but his 36.6 per cent vote share fell far short of what polls had projected. Guillier got 22.7 per cent in the first round and had been counting on support from backers of other left-leaning candidates who were eliminated.

The 64-year-old Guillier was backed by outgoing President Michelle Bachelet, but many Chileans have been disillusioned by lagging economic growth under her watch, a problem based largely on lower international prices for copper, which is the backbone of Chile's economy. Many leftists also feel she wavered on her promises of profound social changes in labour and education policies.

Pinera, 68, struggled with large protests over Chile's inequality and demands for education reform during his first term as president, and left office in 2014 with low popularity ratings. But he also oversaw annual economic growth of about 5 per cent a year.

“I think we'll win these elections and better times will come for all Chileans,” Pinera said after casting his vote in the Chilean capital.

The conservative politician proposes slashing taxes on business to revive growth and vows to launch a $14 billion, four-year spending plan that includes fresh investments in infrastructure.

Guillier, a former TV anchor, promised to continue Bachelet's plan to increase corporate taxes to partly finance an education overhaul, reform the constitution and improve the pension and health care system.

“I came to vote for Guillier because he will continue Bachelet's reforms, and thanks to her I have a son studying industrial engineering for free,” said Genaro Rodriguez, an electrician in Santiago.

Guillier also wanted to diversify Chile's copper-dependent economy and develop alternative sources of energy to lower investment costs.

“I think we're going to win by a tight but clear margin,” Guillier said after casting his vote in his northern desert region of Antofagasta.

During the first round, Beatriz Sanchez of the Broad Front coalition came in third with 20 per cent of the vote. She pledged her support to Guillier.