Diakite has agreed a four-year deal with the Loftus Road club having initially joined on loan last season.
The 23-year-old made nine appearances for Rangers last term, receiving a red card on his debut against Fulham and scoring the winning goal against Arsenal.
QPR boss Mark Hughes told the club's official website: "Samba was a real find for us in January, so we're delighted he's joined us permanently.
"He's a very accomplished footballer and he's made to measure for the Premier League.
"He's got good pace, strength and ability on the ball and he's going to be a great asset for us going forward. There's still so much more to come from him.
"He's only been exposed to the Premier League for a handful of games, so I'm sure he's raring to go and get back into the action again."
Diakite was equally pleased to seal the move.
"It's a dream come true to sign this contract," he said.
"I loved my time here on loan and I couldn't be happier to join QPR on a permanent deal.
"It's a fantastic club to play for and the owners have great plans for the future - I am just delighted to be part of it.
"This is a really exciting move for me."
Borussia Dortmund hears Wembley Calling and are headed to London for the Champions League final.
Ajax has released their away soccer jersey for the 2013/14 season. Get in the Gear.
The adidas Nitrocharge is the most talked about new cleat in years. It was released on May 15 and will take your pitch by storm.
adidas has added some color to the Predator line with this new colorway. Released on May 17. Be the first to own a pair.
The new PUMA evoSPEED 1.2 FG. A great new soccer cleat with classic look and first time for PUMA to be on the cleat.
The push for more color on their cleats, adidas has added the infrared colorway to the adiZero f50 Line.
The Liverpool 2013/14 soccer jersey is available for pre-order. The Reds are eager to compete for silver next season.
One of the top soccer cleats for control the Nike CTR360 will not let you down on the field in tight spaces.
Chelsea won the Europa League on Wednesday. The Blues defeated Benfica 2-1 on injury time goal from Ivanovic.
Bayern Munich are kings of Germany and hope to be crowned kings of Europe at Wembley later this month!