The west London club sign the Cameroon international from Marseille for an undisclosed fee, with former captain Joey Barton moving the other way on a one-year loan deal
The 26-year old has arrived at Loftus Road after joining from Marseille for an undisclosed fee.
|11/1||Man City are 11/1 to beat QPR 4-0 on Saturday
Hughes was quoted previously admiring Mbia's qualities, as he hopes to fill the void that is left by the departure of Joey Barton who moves the other direction in a loan deal.
"He is another player that can play in a couple of positions. I like that flexibility in players. He is a good age, and we have paid a good price for him," Hughes told the club's official website.
M'Bia made 53 appearances for Marseille and will look to take that experience to the Premier League as Mark Hughes aims to make a statement for the 2012/13 Premier League campaign.
QPR have a tasking trip to the Etihad Stadium as they take on Manchester City on September 1. The last time these two sides faced was the dramatic finale of the 2011/2012 campaign that saw City clinch the title.