The provisional results give the PvdA, led by Frans Timmermans, five seats in the European parliament – with turnout the highest since 1989 at over 42 percent.
Timmermans is the lead candidate for the European parliament's social democratic grouping.
Along with Britain, the Netherlands was the first of the 28 EU member states to vote in parliamentary ballot. Irish and Czech voters head to the polls on Friday, with the remaining 24 members voting Sunday.
⏰3 days until the end of #EUElections2019 ⏰Is that the @TimmermansEU effect? - In NL 🇳🇱the exit polls show a surprising result: Dutch Labor Party (18%) doubling the result of 2014. Second strongest are Christian Democrats who lost one seat. Anti-EU parties fall short (11%). pic.twitter.com/FVGyp9nyVjHanover EU (@hanovereu) 24 mai 2019
Strict domestic laws in the UK prevent the publication of exit polls for EU parliamentary elections until all member states have finished voting.
While official results won’t be known until late Sunday, the Dutch Labour party has been celebrating victory, toasting what they called an "unexpected comeback".
In national elections in 2017, the PvDA party plummeted from 38 seats to nine.
In other exit poll results, Prime Minister Mark Rutte’s Liberal coalition was set to win four seats, with the right-wing populist Forum for Democracy on three seats, alongside the left-wing green party GroenLinks.
The anti-Islam Party for Freedom, led by populist lawmaker Geert Wilders, is tipped to lose three of its four seats.