Commentator Ben Coates described the result as "something of an earthquake in Dutch politics".
Although their policies are very much focused on opposing the government's environmental policies, he told the BBC most people would characterise them as a right-wing, populist party that was quite anti-EU, anti-immigration and in favour of banning burkas for Muslims.
Standing before supporters on Wednesday night, Caroline van der Plas wore her trademark green nail polish and a ring featuring an upside-down Dutch flag, a symbol of the anti-government protests.
The daughter of an Irish mother and a Dutch father, she lost her husband Jan to pancreatic cancer as the protests took off in 2019. She is unlike any Dutch party leader - and for many voters, that is her appeal.
She had to step back from public campaigning last year because of death threats. She was told the same fate awaited her as Pim Fortuyn, a populist leader assassinated days before the 2002 Dutch general election.เว็บพนัน
Speaking to the BBC during a visit to farmers in the rural east, she sprang to her feet in mid-sentence to avoid a bee, explaining she had been stung as a toddler and had been terrified ever since.