The "exceptional" manuscript from 1786 which will be auctioned on Wednesday in the French capital comes from the peak of the composer's career in Vienna, the auction house Ader Nordmann said.
Called Scena con Rondo, Mozart wrote the music initially as a recitative to be sung by Figaro's bride, Susanna, before rejecting it for the now legendary aria, Deh vieni non tardar.
"These four pages are particularly important because they reveal Mozart at work, struggling to rethink a scene in the final act of the opera," expert Thierry Bodin told the AFP news agency.
It will be sold along with another Mozart manuscript, a fragment of a serenade to youth written by young Wolfgang Amadeus when he was only 17.
Probably commissioned by the "chancellor of Salzburg, who was a friend of the Mozart family, to mark the end of his son's studies," according to Bodin, it is expected to make between 120,000 and 150,000 euros.
The manuscripts are part of a vast sell-off by the French state of the collection amassed by the collapsed investment firm Aristophil.
It was shut down in scandal three years ago, taking 850 million euros of its investors' money with it.
The 130,000 manuscripts and historical documents that Aristophil had its investors sink their savings into are now being dispersed in auctions over the next six years run by Ader Nordmann and three other French auction houses, Artcurial, Drouot Estimations and Aguttes.