Sports minister Giancarlo Giorgetti submitted a letter to the International Olympic Committee (IOC) providing "all the guarantees, signed by Giuseppe Conte's government", the Olympic body said.
The head of the IOC evaluation commission, Octavian Morariu, on Thursday described the joint bid by Italy's financial capital and Dolomites ski resort Cortina D'Ampezzo as "very, very positive".
The financial guarantee reportedly amount to €415 million.
Under the bid figure skating, hockey and short-track speedskating would be held in Milan, with sliding sports and curling in Cortina; and speedskating, biathlon and Nordic sports would take place at Val di Fiemme, in Trentino.
The alpine skiing events would be in Bormio for the men and Cortina for women while the opening ceremony would be at the San Siro football stadium, with the closing ceremony at Verona's Arena, a large Roman amphitheatre.
Darkening clouds gathering over Italy's economy, but Deputy Prime Minister Matteo Salvini, who has strongly backed the bid, said the government had the necessary funds.
"There is commitment, willing from the government, the cities and the regions... Italy can be the window on the world. So as a native of Milan and an Italian, I am proud of this bid," said Salvini.
"All the data and all the studies of the costs and the profits show that the expenditure incurred to guarantee security and public order at the Games will be largely covered by the profits generated for the country," he added.
The only city in competition with the Italian bid is Stockholm.
The vote to chose the host city will be made in Lausanne on June 24.