Labor has made its biggest arts pledge days out from the election during a campaign in which the sector has barely rated a mention.
The government, which polls tip will return to power after Saturday's vote, committed $35 million for The Fox: NGV Contemporary at the National Gallery of Victoria.
In 2022, logistics magnates Lindsay and Paula Fox donated a record $100 million to build a third NGV gallery, which will be named after them.
The public gallery is part of the $1.7 billion Melbourne Arts Precinct Transformation project, billed as Australia's largest ever cultural infrastructure build.
The Fox will include 13,000sq m of display space for artworks, as well as a rooftop terrace and sculpture garden.
Once constructed, The Fox: NGV Contemporary will be the nation's biggest gallery dedicated to contemporary art, although it is still some years away.
The construction contract for the project was awarded to Lend Lease in March and the gallery is due to open in 2028.
"We know how important arts and culture is to our community and this funding will showcase Melbourne's talent to the world," Arts Minister Tony Burke said on Thursday.
The NGV is Australia's most-visited public art museum with 2.8 million visitors in 2024.
Its most recent blockbuster show, Yayoi Kusama, saw a record-breaking 570,537 visitors over four months, making it the most popular ticketed exhibition the NGV has ever staged.
The expansion project is expected to attract an additional one or two million visitors annually, adding $2.3 billion to the state's economy.
The Fox gallery will be built on the former site of the Carlton & United Breweries building in Southbank Boulevard, behind NGV International on St Kilda Rd.
