Mutu must pay Chelsea €17 million
In July, the Switzerland-based Court of Arbitration for Sport (CAS) upheld a FIFA ruling in 2008 that the striker, 31, had to compensate the English club.
Mutu then appealed to the Swiss Federal Supreme Court which temporarily suspended the fine in October.
But in a statement on Monday, the court said: "The Federal Supreme Court on June 10, 2010, rejected Adrian Mutu's appeal against a decision made by the Tribunal Arbitral du Sport (CAS).
"The CAS had ordered the Romanian football player to pay 17 million euros to his former employer, Chelsea Football Club Limited (Chelsea)."
Mutu, who now plays for Fiorentina in Italy, is currently suspended until Oct. 29 for testing positive for a banned appetite suppressant.
A Chelsea spokesman said the club would not comment on the court ruling.