One of the exit polls showed New Democracy, led by opposition leader Kyriakos Mitsotakis, winning between 155 and 167 seats in the 300 member parliament. It showed ruling Syriza coming second with between 26.5 and 30.5 percent of the vote.
Sunday's poll was the first national election since the country shook off close scrutiny by its European partners who loaned Greece billions in three bailouts. Incumbent Prime Minister Alexis Tsipras signed up to the latest, in 2015, in return for potential debt relief.
"The basic reason (for the result) is the economy," said analyst Theodore Couloumbis. "In the past 4.5 years people saw no improvement, on the contrary, there were cutbacks in salaries and pensions," he said.
The snap election was called after Syriza suffered a defeat in European elections in May.
Greece endured a debilitating financial crisis from 2010 that required three cash lifelines from its European Union partners. The economy is the public's main concern, said Thomas Gerakis of pollsters MARC.
Tsipras said a vote cast for Mitsotakis would go to the political establishment, which forced Greece to the edge of the precipice in the first place.
While economic growth has returned, Greek unemployment of 18 percent is the euro zone's highest.
New Democracy has promised to invest in creating well-paid jobs with decent benefits. The outgoing government meanwhile hopes voters will reward it for upping the minimum wage by 11 percent and reinstating collective bargaining.
Its leader has promised to lower taxes and social security contributions, maintain aid to the needy, attract foreign private investments and create a "rampant" economy.