The ex-Tottenham centre-back, 34, who played 76 times for Pompey before leaving when his contract expired at the end of last season, has put pen to paper in time to be included in the squad for Tuesday night's visit of Leyton Orient.
"I'm delighted to be back at Pompey and to have the chance to help out Guy and this great club," the former Portugal international told Pompey's official website.
"I can't wait to get out on the pitch again and play in front of the fantastic supporters at Fratton Park." Caretaker Pompey boss Guy Whittingham said:
"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."
Meanwhile, Portsmouth have also confirmed that on-loan defender Carl Dickinson has been recalled by parent club Watford.