Cas Mudde, a professor of international affairs at the University of Georgia in the United States, said he was "sceptical about people reading European trends into" the Dutch vote. "It's idiosyncratic and doesn't mean anything for other Social Democratic parties."
The Forum for Democracy of Dutch nationalist Thierry Baudet, which had been polling neck and neck in first place alongside the conservatives of Prime Minister Mark Rutte, ended fourth. Geert Wilders' anti-immigration Freedom Party fell to 4%, its worst showing since it was established in 2006.
No opinion poll before the vote had put Labour anywhere better than third place, but it ended first with 18 percent, three points ahead of Rutte's ruling centre-right VVD.
Baudet may have lost strong momentum in the final week of campaigning after publishing a book review that questioned whether women can both work and have children, and retweeting a video that was hosted by a German white supremacist group.
In Britain, a YouGov poll on Wednesday had put support for Farage's Brexit Party, which is campaigning for Britain to leave the European Union immediately and with no divorce deal if necessary, at 37%. May's Conservatives, deeply divided over Brexit, had just 7%.
In France, Marine Le Pen's eurosceptic National Rally leads opinion polls, slightly ahead of President Emmanuel Macron's strongly pro-EU Republic On the Move party, according to a survey published by Les Echos newspaper on Thursday.
In Germany, Chancellor Angela Merkel's conservatives are expected to remain the largest party, with the far-right Alternative for Germany seen only in fourth place at 12%.
Italy's far-right ruling League party, led by Deputy Prime Minister and Interior Minister Matteo Salvini, is seen remaining the country's largest.
