Diop, 34, has been issued with a visa by the British Embassy in Paris and his registration subsequently approved by the Football League and Football Association.
The Senegalese midfielder is likely to have to wait for his full Blues debut, however.
Blues 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."
The Liverpool 2013/14 soccer jersey is available for pre-order. The Reds are eager to compete for silver next season.
Borussia Dortmund hears Wembley Calling and are headed to London for the Champions League final.
The new PUMA evoSPEED 1.2 FG. A great new soccer cleat with classic look and first time for PUMA to be on the cleat.
The push for more color on their cleats, adidas has added the infrared colorway to the adiZero f50 Line.
Bayern Munich are kings of Germany and hope to be crowned kings of Europe at Wembley later this month!
Ajax has released their away soccer jersey for the 2013/14 season. Get in the Gear.
The Juventus jersey for the 2013/14 was released earlier this week. Be the first to wear the colors of the Old Lady.
One of the top soccer cleats for control the Nike CTR360 will not let you down on the field in tight spaces.
Chelsea won the Europa League on Wednesday. The Blues defeated Benfica 2-1 on injury time goal from Ivanovic.
The adidas Nitrocharge is the most talked about new cleat in years. It was released on May 15 and will take your pitch by storm.