The 31-year-old parted company with Inter on Friday when the Italian Serie A side released him from the final year of his contract.
With an eye on regaining his place in the national team for the 2006 World Cup Vieri turned down a host of offers from foreign clubs to remain in Italy.
Inter president Massimo Moratti took the news of the player's departure to his club's bitter rivals on the chin.
"He's done what he wanted to do and I certainly wasn't able to stop him he said.
"But all the same I don't feel betrayed and a front line of Andriy Shevchenko-Vieri doesn't frighten me he added.
Vieri arrived at Inter in the 1999-2000 season after a year at Lazio and one season with Atletico Madrid.
Top scorer in Italy in 2001 with 27 goals he was dogged last season by a series of injury problems.
Vieri who has 45 international caps but was left out in the cold in the recent round of World Cup qualifiers is likely to take the place of another former Inter forward Argentine striker Hernan Crespo.
Crespo has been on loan but is probably going to be reclaimed by English Premiership champions Chelsea.