The left-wing Smer-Social Democracy party of former premier Robert Fico won a parliamentary majority in Saturday's election, near-final results showed Sunday.
With votes from almost 95 percent of polling stations counted, Smer looked set to secure almost 45-percent voter support and gain 84 seats in the 150-seat parliament, the Slovak Statistics Office said on its website.
"The result is a very nice surprise, the number of parliament seats shows Smer has succeeded with its programme," Fico told reporters early on Sunday.
"Smer can now fully implement its programme... of a welfare state, of improving the condition of public finances, not at the cost of low-income groups," he added.
"The programme will be pro-European... we want the eurozone preserved and the euro as a strong European currency," said Fico, whose previous government ruling in 2006-2010 led the ex-communist country of 5.4 million people to the eurozone in 2009.
He added his party would seek cooperation with the other parties that will make it to the parliament.
The Christian Democrats and newly-formed right-wing Common People party came second in the vote with 16 seats each, and the ethnic Hungarian Most-Hid would get 14 seats.
The ruling right-wing SDKU-DS party, crimped by a corruption scandal that hit the country before the vote, saw voter support sink from 15 percent in the 2010 election to 5.8 percent or 11 seats.
The liberal right-wing SaS would also make it to parliament, getting 10 seats.