The club acquired the services of Klaus Jensen for 1.25 million pounds. The 27-year-old player signed a three-year contract.
"Knowing his excellent passing and skills in playing without the ball, I believe he will become an important part of the team," said Fulham coach Chris Coleman.
In July 2000, Charlton paid 4 million pounds for C. Jensen, who had previously played for the club.
"After speaking with Chris Coleman and seeing the club facilities, I am more than happy to move from the south to north London, and I think it is the right direction for my career," said the player.
Meanwhile, Charlton coach Alan Curbishley had to admit defeat in the battle for one of the club's best safeties.
"Klaus had a contract with the club for another year, but he made it clear to us that he did not want to renew it," said the coach. "He also said he no longer wanted to play for the club because he needed new challenges. As soon as Fulham offered a contract, it was clear that he would accept."