The French Football Federation (FFF) said a mask will be made for their captain, but it is not yet known if he will play against the Netherlands on Friday.
The 25-year-old forward was forced off during Monday’s 1-0 win over Austria after his face hit opponent Kevin Danso’s shoulder in the follow-through from an aerial challenge.
He was taken to Dusseldorf hospital where the break was confirmed.
“He has returned to the base camp of the French team,” the FFF said.
“He will undergo treatment in the coming days, without undergoing surgery immediately.”
Following the collision, France wanted to replace Mbappe with Olivier Giroud but play restarted without allowing them to make their change.
Mbappe went back on to the pitch without permission and sat down – picking up a yellow card – before the substitution was made.
In the post-match news conference, boss Didier Deschamps said their number 10 was “not doing well” and added “his nose got badly hit”.
“We need to check it out but it seems quite complicated, which is really very unfortunate for us. He didn’t get off lightly.”
Mbappe, who has scored 47 goals in 80 appearances for France, will be integral to their hopes of winning a third European title.
He had a hand in France’s only goal as his cross was headed into his own net by Max Wober.
After the match, Danso said on X: “I wish him a good recovery and I hope he can quickly get back on the pitch.
“To French supporters: I am sorry that Kylian Mbappe was injured from our duel.”
Mbappe, who has yet to score a Euros goal to add to his 12 World Cup strikes, will join Real Madrid from Paris St-Germain this summer.
Deschamps was asked if he could miss their next game against the Netherlands on Friday.
“I’m not going to go into hypothesis but the French team with Kylian will always be stronger with him,” he said.
“If the news doesn’t go along these lines then we will have to fight without him.”
Team-mate Adrien Rabiot told reporters, external Mbappe had said “maybe he’ll be ready for the third match” against Poland next Tuesday.
