The former Southampton player has signed a two-and-a-half-year deal with the option of a further year.
Lemina joined Nice in 2021 and has made 22 appearances for them this season, scoring once.
“Mario is a good player,” Wolves boss Julen Lopetegui said.
“We know him, he wants to be here, and he knows the English league. I think that he has the profile to be a good player for us. That’s why he’s here and I wish him all the best.
“He has the profile to help us to improve and to be able to improve our performance in the next matches.”
Sporting director Matt Hobbs said the club had been tracking the player for some time.
“He isn’t someone who has come up since Julen came in, he’s a player were able to sign in the past but hasn’t progressed to this point until now. Our scouting team pushed him last summe…