The 31-year-old has signed a two-year contract with QPR and joins the club for an undisclosed fee.
“This is a real coup for QPR,” QPR boss Mark Hughes told the club’s official website. “We are delighted Ji is going to join us because his record speaks for itself.
“He has been a big player for Manchester United and played a big part in their success in recent years.
“He is hugely respected there because of what he has achieved, his application to his work and the impact he has on games.
“He was always picked for the big matches because they could rely on him, and we are going to reap all those qualities.
“I think it is fair to say Ji has been attracted not to where QPR are, but where QPR are going.
“We were able to show him where the club is heading and he embraced it. Ji gets what we are trying to do. This is a huge signing for this football club.”
Park told QPR player: “The project was simply too good to resist and I am excited about getting started in pre-season and going on tour to Asia in the coming days.
“I am joining a club that is very much on an upward curve – a club that has a very bright future.”
“I am overjoyed and can’t wait to see him in a QPR shirt,” QPR owner Tony Fernandes added.
“It shows our determination and our ambition to build this club.
“Ji is a global star with a Champions League winner’s medal to his name, and he is as excited about this move as we all are.”