The 30-year-old allegedly tried to get rid of the stash by switching her suitcase with a colleague's after the landing in Milan from Lahore, Pakistan, Corriere reported.
The Pakistan International Airline flight, which was destined for Paris, was forced to land in the northern Italian city after police were tipped off that someone on board had drugs.
Police said the woman acted “nervously” at baggage reclaim.
She was arrested after 8.7 kilos of "pure heroin" was found in her suitcase, Corriere reported.
The woman was taken to a prison in Monza, a town in Lombardy.