The 32-year-old re-joined Milan from Real Madrid last summer, but has struggled to reproduce his best form at the San Siro.
Talk of a move to the MLS has gathered pace in recent months and Orlando have revealed via a statement that the Brazilian is close to agreeing terms.
"Orlando City Soccer Club is in advanced discussions with Kaka," read the statement.
"Pending completion of the potential player agreement, Kaka would join Orlando City SC in January 2015 prior to the club's first season in Major League Soccer.
"The club will have no additional comment until further notice."
Kaka has scored 29 times in 87 games for his country, but is not part of their squad at the World Cup this summer.