The 31-year-old, who was a free agent after leaving Malaga, was greeted by more than 2,000 jubilant Olympiacos supporters as he arrived at the club's offices to put pen to paper on a two-year deal.
"I would like to thank the supporters who came out to welcome me and have showed me such love in my first moments here in Athens," Saviola said as he posed for photographs with the number nine jersey he will wear.
Saviola's arrival in Greece is by far the highest-profile transfer of what has been a quiet close season in the crisis-hit country's Super League.
"I am very happy to be here," he added.
"I have a lot of desire and motivation to get to know my team mates and start training. I hope that we will manage to achieve great things this year."
Buenos Aires-born Saviola showed promise as a teenager, making his debut for River Plate at the age of 16 and helping the club to the 1999 Apertura and 2000 Clausura championships.
He earned the 1999 South American Footballer of the Year award before moving to Barcelona in a 15 million euro deal in 2001.
He scored 49 goals in 123 appearances at the Nou Camp and also had loan spells at Monaco and Sevilla before leaving Catalonia for Real Madrid in 2007.
After two years as a fringe player at Real, Saviola went on to play for Benfica and Malaga, scoring eight goals in 27 matches for the latter last season.
Saviola joins fellow Argentines Ariel Ibagaza, Tomas De Vincenti and Alejandro Dominguez at Olympiacos , who are coached by Spaniard Michel.
- Sports & Recreation