An ally of the Georgian prime minister has won the presidential election outright, according to partial results from the electoral commission.
With votes at 12% of polling stations counted, Giorgi Margvelashvili has won 64%. His closest rival, David Bakradze, trails with 21%.
Mr Bakradze has admitted defeat and congratulated Mr Margvelashvili.
The election marks an end to a decade in power for pro-Western President Mikheil Saakashvili.
He has served the maximum two terms, and told voters to "respect the opinion of the majority".
As Mr Margvelashvili - a former academic handpicked by Prime Minister Bidzina Ivanishvili - looks to have secured more than half the vote, the contest looks unlikely to go to a second round.
Mr Ivanishvili and Mr Saakashvili are bitter political rivals.
Giorgi Margvelashvili is a member of Mr Ivanishvili's Georgian Dream party, which won parliamentary elections last year, ushering in the former Soviet republic's first legal transfer of power.
The billionaire businessman intends to resign as prime minister within weeks of the vote, saying he has achieved his aims.
He has called the vote Georgia's first "European-style election".
The success of Mr Margvelashivili over Mr Saakashvili's ally, Mr Bakradze, cements Georgian Dream's hold on power.
Since coming to power in the bloodless 2003 "Rose Revolution" outgoing President Saakashvili has implemented reforms which helped root out corruption.
He pursued a pro-Western foreign policy and improved public services in the Caucasus republic, where poverty remains widespread.
Tensions with Moscow flared up into an armed conflict in August 2008.
The country's prime minister, who is also Georgia's richest man, has dismissed Mr Saakashvili's achievements, calling him a "liar" and a "dictator".
He has indicated that Mr Saakashvili could face questioning or even prosecution over the alleged crimes of his government after his term ends.
Mr Ivanishvili has not yet named his party's successor as prime minister.