Meloni, as leader of the largest coalition party, is also likely to become Italy's first female prime minister.
Meloni, 45, plays down her party's post-fascist roots and portrays it as a mainstream conservative group. She has pledged to support Western policy on Ukraine and not take undue risks with the third largest economy in the euro zone.
However, the outcome is likely to ring alarm bells in European capitals and on financial markets, given the desire to preserve unity in confronting Russia and concerns over Italy's daunting debt mountain.
An exit poll for state broadcaster RAI said the bloc of conservative parties, that also includes Matteo Salvini's League and Silvio Berlusconi's Forza Italia party, would win both houses of parliament.
"Centre-right clearly ahead both in the lower house and the Senate! It'll be a long night but even now I want to say thanks," Salvini said on Twitter.
Italy's electoral law favours groups that create pre-ballot pacts, giving them an outsized number of seats compared with their vote tally.
RAI said the right-wing alliance would win between 227 and 257 of the 400 seats in the lower house of parliament and 111 to 131 of the 200 Senate seats.
Full results are expected by early Monday.
The result caps a remarkable rise for Meloni, whose party won only four per cent of the vote in the last national election in 2018, but this time around was forecast to emerge as Italy's largest group with 22 to 26 per cent.
But it was not a ringing endorsement, with voter turnout of 64.1 per cent down from 74 per cent four years ago - a record low number in a country that has historically enjoyed a high level of voter participation.
Italy has a history of political instability.
The next prime minister will lead the country's 68th government since 1946 and face a host of problems, notably soaring energy costs and growing economic headwinds.
The election was triggered by party infighting that brought down prime minister Mario Draghi's broad national unity government in July.
The new, slimmed-down parliament will not meet until October 13, when the head of state will meet party leaders to decide the shape of the new government.
