Italian soccer has been hit by a match-fixing scandal and hooligan problems in recent years while its top teams were humbled by English sides in last season's Champions League.
Big names such as Chelsea's Frank Lampard, a target for Inter Milan, shunned Serie A and the arrivals of Ronaldinho and David Beckham at AC Milan were greeted with scepticism by some fans and pundits who believe they are past their best.
"It is an important sign for all Italian football," Italian league president Antonio Matarrese said in a statement.
"Financial resources have not come but an asset has stayed. It is a matter of great prestige which enriches the value of Milan and our league."
Brazil forward Kaka, a quiet and religious man with mesmerising skill, has turned down the world's richest club and reported earnings that have never been seen before in soccer.
City have slightly disputed Milan's and Kaka's version of events, saying they never had a chance to make him an offer, but the 26-year-old could have demanded to leave if he wanted.
Milan, who won their seventh European Cup in 2007 thanks to Kaka's brilliance, were bound to consider a world record offer which reports said was about 110 million euros ($143 million).
Some commentators have suggested the whole saga was a big publicity stunt by Milan and owner Silvio Berlusconi, but there is no doubting the emotion Kaka felt at last Saturday's 1-0 home win over Fiorentina in Serie A.
Fan demonstrations outside Milan's club offices and Kaka's home also showed him that he would struggle to have the same bond with supporters anywhere else in the world.
