The former Germany captain believes the Portuguese's long awaited Stamford Bridge return is a superb decision and expects the Blues to improve under his guidance
Mourinho was confirmed as Chelsea's new manager following months of speculation and Ballack, who was signed by the 50-year-old back in 2006, believes it is a great appointment for both parties.
"To have Jose Mourinho at Chelsea is a fantastic decision," he told Sky Sports.
"He is a great character and a great coach. Even at his age he has had unbelievable success.
"To go back to a club like this, it is never a bad decision. Chelsea are a fantastic club - they won the Champions League last year and this year the Europa League.
"The money will be right for him, the fans love him, he has a lot of English supporters, even if they don't support Chelsea.
"Altogether it is a great package for him."
Ballack made over 100 appearances for the west London side scoring 17 goals.