Though the fee remains undisclosed as at the time the information reached us but it is to be around the forward’s release clause of seven million pounds.
The Senegal international will wear the number 29 shirt for the Blues and will be eligible to feature in Saturday’s FA Cup tie away to Southampton.
The striker, who becomes the first Senegalese player to play for Chelsea, has hit 13 goals in the Premier League so far this season.
The striker has been on an 18-month spell for Newcastle United, but before then Demba Ba has been top of the club’s goal scoring charts this season.
Ba said “It feels good to be here, I’m very happy and very proud.” after the signing.
“It was important for me, and for Newcastle, to get my future sorted and now we can move on. Now they have the whole month to buy someone and for me as well, the sooner the better. Now I am here I just need to get settled in.
“When the club who won the Champions League wants you, the decision is very easy. This club is massive and that’s something that helped the decision a lot. It was not a hard one.”