Real Madrid's top summer target is believed to be Monaco youngster Mbappe, who has scored 19 goals in 32 games this season.
The 18-year-old is also wanted by Manchester United, who have eyed the teenager as an alternative to Antoine Griezmann.
But Fabinho believes the Frenchman will end up at either Real Madrid or Barcelona.
Fabinho claims Man Utd target Kylian Mbappe will join Real Madrid or Barcelona
“We know that sooner or later he will end up at Real Madrid, Barcelona or a club of that calibre," he told Brazilian outlet Chuteria FC.
"But so long as he is still with us, we are going to profit from that!”
Fabinho has also been linked with a move away from Monaco, but he claims he has not been contacted by any clubs regarding a move.
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Fabinho claims he has not been contacted over a move
“Certainly, numerous offers will arrive for several players, even though we are very young," the Brazilian added.
"We have five players in the French national team, it is incredible. I have not yet been contacted by clubs, I do not like to think about that too much, because the window only begins in June and we are still in the running for four competitions.
“My contract runs until 2021 and I do not know what the plans of the board are for next season.
"If they are looking to keep the team together, if they are looking to sign reinforcements, if they are looking to sell… We will wait and see what happens.”