The QPR midfielder has spent the season on loan at Fulham thus far, but will cut his stay at Craven Cottage short to join the Rossoneri.
He has now touched down at Linate airport before completing his transfer to San Siro.
"Adel Taarabt, the 24-year-old Moroccan attacker, landed at Milan Linate on a private flight," a club statement read.
"AC Milan will have to wait for the usual procedures before his transfer becomes official."
Taarabt will be the second player plundered from west London by Milan this January, with Michael Essien having already joined the club from Chelsea.
The France-born playmaker began his career at Lens before sealing a move to Tottenham at the age of 17. He first joined QPR in 2009 and sealed a permanent switch to Loftus Road in 2010 after two loan spells.
Following Harry Redknapp's side's relegation from the Premier League last season, he moved to Craven Cottage, but netted only once in 16 appearances for the club in all competitions.