The ministry of culture has been working on the project for several months with the idea to keep the famous sites open seven days a week first mooted back in July.
Confirmation of the government’s plan came in the draft 2015 Budget which was presented to the cabinet on Wednesday.
“The opening of the country’s three most-visited museums seven days a week will improve the access offered to the public and better access to the works of art,” reads the text of the draft budget.
The necessary recruitment so the museums can open all week round will also be carried out, the text says.
The ministry added it would hold consultations with the necessary social partners and that the "net economic effect would be positive", with ticket receipts outweighing the costs involved. The week-long openings are expected to come into force from next year.
Unlike comparable institutions in other parts of the world, the museums currently close one day per week, usually on Monday or Tuesday.
In London, top museums such as the National Gallery or the British Museum are open every day of the week. Similarly the Museum of Modern Art in New York.
The Louvre, home to Leonardo da Vinci's Mona Lisa, is the world's most visited museum, with more than 9.2 million visitors per year.
The Palace of Versailles, to the southeast of Paris, attracts seven million visitors per year and the Musee d'Orsay 3.5 million.
French unions expressed reservations about the announcement. Christian Galani of the CGT union at the Louvre said: "The idea is to get the maximum amount of money possible and there is no thought about the visiting conditions."
"If we open seven days out of seven, we will only be able to open 60 percent of the rooms whereas today, 85 percent of the Louvre is open and the visitor density will rise just as quickly as before," he added.
The Louvre's management told AFP there would be in-depth dialogue with unions "so that the measures are implemented in the interest of visitors and staff".
The CFDT union representing staff at the Palace of Versailles has already pointed to other practical difficulties.
"We will have to do cleaning work at night," the CFDT said in a statement.
"That will cost more because they will have to pay night wages."
Film crews who pay to use Versailles as a backdrop on closed days might also face problems, it said.
The seven-day operation could be welcome news for the Louvre museum's finances which have been hit by a flurry of problems in recent years, including a fake ticket scam and a spike in pickpocket thefts which in turn led to a temporary closure of the museum due to a staff walkout.