Papa Boupa Diop has signed a short-term contract with Championship club Birmingham until 17 November.
The Senegalese midfielder has been issued with a visa by the British Embassy in Paris and his registration was subsequently approved by the Football League and Football Association.
Former Fulham and West Ham midfielder Diop, 34, is likely to have to wait for his full Blues debut and manager Lee Clark said: "I feel we need some sort of physical presence in the middle of the pitch and I know him very well.
"I played alongside him for a while (at Fulham) and we were partners in the centre of the pitch and I know what he's about.
"He's competitive because of his size and his physique. He's competitive in the air and on the floor but when he gets the ball down as well he can play. He's obviously a threat in both boxes from set plays.
"I just felt that was one area as well where we were a little bit loose in a couple of games that we've lost."