The Brazilian has been long been linked with Orlando, who are set to join the MLS from the 2015 season.
Orlando confirmed earlier this month that they were in advanced negotiations with the playmaker, only for Kaka to then insist that he would be staying at San Siro.
However, his second stint with Milan has now come to an end.
A statement on the Milan website read: "AC Milan announces that it has today [Monday] terminated the contract of Kaka by mutual consent."
Kaka rejoined Milan in September last year following a four-year spell with Real Madrid.
The 32-year-old scored nine goals in 37 appearances in 2013-14 as Milan finished eighth in Serie A.
A move to Orlando now appears imminent, although Sao Paulo vice-president Ataide Gil Guerreiro has claimed that they have reached an agreement that will see Kaka go on loan to his boyhood club prior to joining the MLS.
