Campbell, who scored 13 Premier League goals for the Seasiders last season, moves to Loftus Road on a two-year contract.
"I grew up around here and QPR have played a massive part in my life," 29-year-old Campbell told the club's website.
"This was my first club, from 6-16, so to finally be back here at the age of 29 is really special."
Rangers manager Neil Warnock said: "He is someone I have admired for a while now and he had a fabulous season in the Premier League with Blackpool last year.
"He is a QPR fan and you can tell he has a great desire to do well for the club he supports. That shone through when I met up with him - he can't wait to play for us."