The 28-year-old moved on a season-long loan from Racing Lens while Tottenham Hotspur midfielder Jamie O'Hara, who signed a new Spurs contract to 2013 on Friday, also joined on loan until January.
Former England under-21 international O'Hara, who made his debut at Portsmouth in December 2007, has made 56 Spurs appearances and scored seven goals.
Another Spurs midfielder, Kevin-Prince Boateng, and Wigan Athletic midfielder Michael Brown also signed for the south coast club on a permanent basis.
Boateng, 22, agreed a three-year deal after spending the second half of last season on loan to Borussia Dortmund.
"He's a young player who wants to prove something," manager Paul Hart told the club's website.
"He has got tremendous ability and hopefully we can provide the environment to channel that."
Former Fulham and Spurs player Brown, 32, signed a two-year deal with the Fratton Park club.
No transfer fees were disclosed by Portsmouth, who were taken over this week by United Arab Emirates investor Sulaiman al-Fahim.
Portsmouth, without a point from three matches this season, were forced to sell a number of their best players to reduce debts before the takeover was finalised.
