Campbell, who scored 13 goals in the top flight last season, signed a two-year contract with the club he supported as a boy as they prepare for their first Premier League campaign since 1996.
"This was my first club, from 6-16, so to finally be back here at the age of 29 is really special," Campbell, who grew up near QPR's West London stadium, told the QPR website.
"There were other clubs in the Premier League that showed an interest but when I heard QPR were in for me it was an offer I couldn't refuse - this is my club."
Campbell proved a handful for Premier League defenders last season and manager Neil Warnock believes the forward's pace will be an asset.
"He gives us that extra element of pace which we need and I am sure he will prove to be a big hit with the fans at Loftus Road this season," Warnock said.
QPR begin the season at home to Bolton Wanderers on August 13.
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