Exit poll results give just 20 percent to his closest rival, former speaker of parliament David Bakradze, of outgoing President Mikheil Saakashvili’s United National Movement party.
Ivanishvili’s coalition beat Saakashvili’s party in parliamentary elections a year ago. The prime minister said he will step down next month and nominate a new prime minister, who under Georgia’s new parliamentary system will assume most of the powers previously held by the president.
Saakashvili has been Georgia’s president for 10 years. The constitution barred him from running for a third term. He came to power during the popular uprising that forced President Eduard Shevardnadze to step down in 2004.
The pro-Western Saakashvili’s time in office has included economic reforms and efforts to fight corruption, but also a brief war against Russia and accusations of human rights abuses.