Four weeks since Donald Trump's stunning US election victory and five months after Britons voted to leave the EU, polls put the anti-immigration Hofer neck-and-neck with independent ecologist Alexander Van der Bellen.
Austria's presidency is largely ceremonial, but a win for Hofer would be a major prize for Europe's anti-establishment parties ahead of elections next year in France, Germany and the Netherlands.
The vote takes place the same day as an Italian referendum on constitutional reforms that could spell the end of Prime Minister Matteo Renzi and renewed political upheaval in Europe's fourth-biggest economy.
It ends an 11-month campaign marathon that has been ugly by Austrian standards.
Hofer posters were defaced with Hitler moustaches and Van der Bellen's with dog excrement. His security detail was beefed up after death threats.
Hofer, 45, came top in the first round on April 24th, knocking out for the first time in the post-war period candidates from the two centrist parties that have long dominated Austrian politics.
In a May 22nd runoff, Hofer lost by just 31,000 votes to Van der Bellen. But Hofer's Freedom Party (FPÖ) secured a re-run because of procedural errors. The rematch was then postponed because of faulty glue on postal votes.
Hofer, echoing Trump, has stoked and profited from a growing sense of unease about globalisation and multiculturalism, even though wealthy Austria is one of the biggest winners of European integration.
Despite migrant numbers falling sharply since 2015, the FPÖ has managed to keep immigration on voters' minds by playing on fears of terrorist attacks and of a parallel Islamic society that supposedly rejects Austrian "values".
"There is huge frustration," political analyst Thomas Hofer (no relation) told AFP. Voters are "flocking to populist movements and the easy answers that are offered by those parties."
But Hofer also has struck a more moderate tone than FPÖ chief Heinz-Christian Strache, who called German Chancellor Angela Merkel "the most dangerous woman in Europe" and has warned of "civil war".
With his ready smile, moderate tone and the slogan "unspoilt, honest, good", Hofer won over many centrist voters who in previous years would never have supported the FPÖ, a party long accused of having ties to neo-Nazis.
But at times he has visibly lost his cool and behind the grin Hofer is a steely key ideologue within his party.
Islam, he has said, "has no place in Austria" and is a religion "that sees the whole world as a battleground". And Van der Bellen, his opponent, is a "communist" and a "green dictator".
"My wife, who goes to church every Sunday, says that she would vote for Hofer if it wasn't for all the people behind him in the FPÖ," Werner, a pensioner walking his black-and-white dog in Vienna, told AFP.
'You'll be amazed'
Van der Bellen, 72, a somewhat scruffy economics professor, has at times made it easier for Hofer by coming across as too left-wing, wooden and old. His main strategy has been simply that he is not Hofer.
What a Hofer victory might mean is unclear. Hitherto unused presidential powers could, in theory, allow him to fire Chancellor Christian Kern's government.
"You'll be amazed by what's possible," Hofer said before the first round, a comment made much of by Van der Bellen and which Hofer says he regrets having uttered.
More realistically, though, his victory could prompt Kern and the centre-right to pull the plug on their unhappy coalition and call early elections. And leading the polls right now is the FPÖ.
Hofer's election run "is only one part of a longstanding effort to make an FPÖ-led government, with real executive power, achievable by the next parliamentary election," said Charles Lichfield from the Eurasia think-tank.
By Simon Sturdee