The 34-year-old exited the club when his contract expired in the summer, but he has revealed his delight after returning to Pompey.
"I'm delighted to be back at Pompey and to have the chance to help out Guy and this great club. I can't wait to get out on the pitch again and play in front of the fantastic supporters at Fratton Park," he told the club's official website.
Meanwhile, caretake boss Guy Whittingham added: "Ric is a great character and the fans love him because of the way he has played for us over the past few years. I don't think there are too many players around who read the game as well as he does."
Rocha has made 76 appearances for Portsmouth.