Bia, 20, joins until the end of the season with an option for Wolves to make the deal permanent in the summer.
Wolves boss Mick McCarthy said: "We've very pleased to have signed Geoffrey.
"He's a player we have been tracking for a while and will add some creativity and firepower to our squad.
"He's an attacking midfielder who can play on the right or the left as well as centrally."
Mujangi has scored seven times in the Belgian First Division with Charleroi in 48 appearances.
He has also scored twice in six games for Belgium Under-21s and went on to make his senior international bow against Chile last May.
The player said: "I've played in England once before with Belgium Under-21s and it's been my dream to play in the Premier League."
Wolves chief executive Jez Moxey added: "Geoffrey comes to us with excellent credentials and because he is only 20 years old, he has enormous potential.
"He is highly respected in Belgium and regarded as one of their most talented young players."