Benayoun, who has played for West Ham, Liverpool, Chelsea and Arsenal in the Premier League, has agreed a deal until the end of the season.
Rangers manager Harry Redknapp believes the Israeli midfielder will give his squad an added attacking option.
"Yossi is a good footballer, a top-class player," he told the club's website.
"He's got great ability and is someone I have always liked. I actually tried to take him to Tottenham at one time.
"I think he will be a fantastic addition to the squad.
"We have got a lot of fixtures coming up over the Christmas period and in the New Year, so we are going to need a good squad of quality players for that."
Benayoun, who could make his debut against Blackpool this weekend, added: "I am delighted everything is done and am very pleased to join QPR.
"I have been training here for two weeks and now I can't wait to get involved and help the team.
"The manager was a very big factor for me. He showed me from the beginning that he really wanted me, and he is someone I have always wanted to play for so I am very happy.
"I have played in the Premier League for the last eight years and I enjoy England very much. The Championship is also a great league and I am looking forward to playing in it and helping QPR build on a great start to the season."