Hughes's arrival on a free transfer follows the news that Danny Simpson is set for a spell on the sidelines owing to a back injury and R's boss Harry Redknapp is delighted to add the versatile Northern Ireland international to his squad.
The 34-year-old has played 88 times for his country and Redknapp told the QPR website: "Aaron's a very experienced player and, with the injuries we've suffered lately, he's a fantastic addition.
"He's got pace, excellent positional sense and is a good out-and-out defender.
"He's a great professional and he'll be a big asset to us."
Hughes had made 17 appearances in all competitions for the Cottagers this term and said: "I don't see this as a drop down in class, I see it as a fresh, new challenge.
"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.
"Harry tried to sign me as a youngster when he was at West Ham, so it's nice that I've now got the opportunity to play for him.
"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."
Young Brazilian striker Guilherme Dellatorre then swiftly followed Hughes in at Loftus Road after signing on loan from Desportivo Brasil.
Redknapp added: "He's a young player from Brazil, who our scouts have watched and like."