The midfielder completed a move from Newcastle United in August 2011.
The 30-year-old has endured a turbulent time in the capital, with QPR eventually agreeing to send him on loan to Marseille over the summer.
A misconduct charge picked up on the back of a sending-off at Manchester City on the final day of last season proved to the final straw for the R's.
It was, however, suggested that there could be a route back for Barton after Mark Hughes was relieved of his managerial duties and replaced by Harry Redknapp.
Those bridges would now appear to have been burned, with Barton's claim that he only joined QPR for the money unlikely to endear him to the club's fan base or their new coaching team.
"When I went to QPR it was a choice dictated by money," the brutally honest midfielder told the Sunday People.
"I didn't like what I had done, and I swore I'd never do that again.
"It was the first time in my life that I had taken a decision for money. I did it because my partner was due to give birth - but I did not feel good about it."