Smer-Social Democracy of former prime minister Robert Fico is a clear winner with 44.4 per cent of the vote, or 83 seats in the 150-seat parliament.
President Ivan Gasparovic said he would formally ask Mr Fico to form a new government.
The result allows Mr Fico to govern alone. One party rule has not happened in Slovakia since the split of Czechoslovakia in 1993.
Mr Fico offered opposition parties a chance to join forces and form a two-party coalition government yesterday, but the other parliamentary parties rejected his offer. Before the election, Mr Fico had discussed the necessity of creating a strong, stable government, possibly formed by two parties, amid another economic downturn and efforts to save the eurozone.
Mr Fico has pledged to maintain a welfare state, increase corporate tax and hike income tax for the highest earners.
“We succeeded with what we offered as an alternative,” Mr Fico said. “We’ve achieved a result that is a pleasant surprise for us, to be honest.”
The outgoing centre-right, four-party coalition received a combined 51 seats, on the back of voter anger over a major corruption scandal.
The new Ordinary People party that campaigned on an anti-corruption ticket won 16 seats, while the ultranationalist Slovak National Party, known for derogatory comments about ethnic Hungarians, Roma and political opponents, ended below the 5 per cent threshold needed to win parliamentary representation.
Turnout was 59.11 per cent. Analysts had predicted a record low turnout, as voters were expected to register their anger over allegations that a private financial group bribed government and opposition politicians in 2005-06 to win lucrative privatisation deals.
The “Gorilla” files – posted online by an anonymous source in December and said to be based on wiretaps – have rocked Slovak politics. One former economy minister is said to have received the equivalent of £8.3 million for his assistance.
Outgoing prime minister Iveta Radicova’s Slovak Democratic and Christian Union was hard hit by the allegations. Ms Radicova’s party was in power in 2005-06 and the then-prime minister, Mikulas Dzurinda, is now the foreign minister and party chairman. The party won 5.9 per cent of the vote, despite overseeing an economic boom.
“It’s clear ... Gorilla is to blame,” Mr Dzurinda said. “It’s a serious loss.”