Chelsea's appeal successful in overturning transfer ban
The Blues were hit with an 18-month transfer embargo in September after Fifa ruled that they were guilty of inducing Kakuta, then 16, to break a contract with Lens back in 2007.
A statement from CAS read: "The Court of Arbitration for Sport (CAS) has issued an award today ratifying the agreement reached by Chelsea FC, Racing Club de Lens and the French football player Gael Kakuta, putting an end to this arbitration procedure which also involved FIFA.
"The CAS has noted that, in the agreement, the two clubs and the player have recognised that the contract between the player and RC Lens was not valid.
"Accordingly, the player could not have terminated it prematurely and without just cause and FC Chelsea cannot therefore be liable for inducing a breach of contract.
"As a consequence, in light of these new circumstances, the sanctions imposed upon Chelsea FC and the player by the FIFA Dispute Resolution Chamber had to be lifted."
"We are pleased to have come to an amicable resolution of the matter and that it has been ratified by CAS and recognised by FIFA," Chelsea chairman Bruce Buck told the club's official website.
"It was always our intention to work together with Lens to reach this end, and both clubs have strengthened their relationship as a result of resolving this case to everyone's satisfaction.
"In an act of good faith and with a view to the possibility of future collaboration with Lens, and without recognising any liability, Chelsea has agreed to pay compensation costs for the training given to the player while at Lens, as mandated by FIFA in its original ruling."