Slovaks, angered by a corruption scandal and weary of government austerity measures, threw their support in weekend parliamentary elections behind a left-leaning politician who has pledged to raise taxes on companies and the wealthy.

Robert Fico's Smer-Social Democracy party won a clear legislative majority, capturing 83 of the 150 seats in the national assembly—the first time since independence in 1993 that a single party has received enough votes to govern on its own, without coalition partners.

The victory for the Slovak left is a sign of mounting frustration among Europeans who have endured years of budget cuts and have yet to see sustained economic benefits. It also shows the pressure on politicians caught between their constituents' desires and the European Union's fiscal rules.

At-times violent anti-austerity demonstrations forced the resignation of Romania's center-right prime minister this year. And France's Socialist presidential candidate François Hollande is leading in the polls while promising to rethink Europe's approach to austerity.

"We succeeded with what we offered as an alternative," said Mr. Fico, who struck a chord with the electorate by arguing that the previous administration had been too hard on the poor and not focused enough on job creation in a country where unemployment is around 13%.