Diakite has joined the Premier League side on loan for the rest of the season, with a view to a permanent deal.
"It is a dream to join a Premier League club," Diakite told the club's official website.
"The board and the manager have big ambitions to achieve and I am delighted to join a club with such goals.
"I have always enjoyed watching English football and I can't wait to return from the African Cup of Nations and give my all for the club. It is a very exciting move for me."
QPR boss Mark Hughes said: "Samba is a young player who has made an impression on French football.
"There has been a lot of interest in him from top clubs in France so we have done really well to get him in.
"He is a good age, has got strength, power, can carry the ball and can score goals from midfield on occasions.
"He will give us more physical presence and athleticism in the middle of the park so he is going to be a good addition."