The 34-year-old, who joined Fulham in 2007, said that he is looking forward to this new challenge in his career and hopes to help QPR win promotion back to the Premier League.
"I don't see this as a drop down in class, I see it as a fresh, new challenge," he told the club's official website. "It's a chance for me to come and get some games and help this club build on what's been a good season so far.
"It's a different challenge but one I'm really looking forward to. The opportunity to come here was too good to turn down. QPR are a club looking to get back into the Premier League and if I can come in and help in some small way, I'll do my best to do that."
Hughes has been given the number 18 shirt at his new club.