Zlatan Ibrahimovic landed at Linate Airport ahead of undertaking his Milan medical on Thursday.
Milan chief football officer Zvonimir Boban and a number of fans were in attendance to greet Ibrahimovic ahead of his return to San Siro.
The 38-year-old striker agreed a six-month deal, with the option for another year, with the Rossoneri last Friday.
Upon completing his medical, Ibrahimovic is expected to sign his contract and head to Milanello to meet coach Stefano Pioli and his new team-mates.
Ibrahimovic, who previously played for Milan from 2010 until 2012 and won the Scudetto and Supercoppa Italiana, became a free agent after deciding to leave LA Galaxy at the end of their MLS campaign in October.
Milan sit 11th in Serie A and return from the mid-season break with a match against Sampdoria on Monday.