Leonardo is returning to AC Milan this week.
Gianluca Di Marzio's website is reporting Leonardo has reached an agreement with Milan 'in the last few hours'.
The 48-year-old controversially moved to arch-rivals Inter in December 2010, guiding them to a Coppa before stepping down seven months later.
He has since spent time as Paris Saint-Germain's sporting director and Coach of Turkish side Antalyaspor.
Marco Fassone, meanwhile, is also being replaced as chief executive.