The governing party, the conservative ÖVP, will be the second largest with 26 percent, while the social democratic SPÖ is expected to land on 20 percent of the votes, reports the public service company ORF.
Both The Greens and the liberal Neos are expected to receive around 8 percent according to the prognosis.
If the result stands, it means that FPÖ has increased by almost 13 percentage points since the country's last parliamentary election in 2019, while ÖVP has decreased by 11 percentage points.
FPÖ leader Herbert Kickl wants to become the country's new federal chancellor. But the path to achieving this, and whether it will be possible, is unclear despite the election success.
Prior to the election, no parties have stated that they want to be part of an FPÖ-led government. On the other hand, it has been hinted that ÖVP could join a possible coalition with SPÖ and Neos to avoid a potential FPÖ rule.
More than six million Austrians have had the opportunity to vote in Sunday's election.
