The South Korea international, 31, has joined the London club for an undisclosed fee.
Park is manager Mark Hughes' sixth summer capture, joining Ryan Nelsen, Andy Johnson, Rob Green, Samba Diakite and former Old Trafford team-mate Fabio at Loftus Road.
The ambitious club also claim his signing will "put the QPR brand on a global scale", heading up their attempts to break into the Asian market.
Rangers, promoted in 2011, only escaped relegation from the Barclays Premier League on the final day of last season and are determined to avoid a similar struggle next term.
Park leaves United after seven years, during which time he made 203 appearances and scored 27 goals, winning four Premier League titles and the Champions League in 2008.
Source: PA
Source: PA