Javier Adelmar Zanetti was born in Buenos Aires with Italian origins to working-class parents and grew up in the harbour area in the Dock Sud district, one of the city's most notorious areas. His father Rodolfo was a bricklayer and his mother Violeta Bonnazola was a cleaner. He began playing football on a field in the city suburbs, maintaining the pitch in his spare time. When he was a teenager, he tried out for local club Independiente's youth academy but was ultimately rejected and told that he lacked the physique to succeed in the game.

After the arrival of Maicon at the beginning of the 2006-07 season, Zanetti was moved from the right-back position into midfield. He ended a four-year goal drought when he scored on 5 November 2006 at a home match against Ascoli, having previously scored on 6 November 2002 at an away match against Empoli. On 27 September 2006, against Bayern Munich, Zanetti played his 500th professional match for Inter and on 22 November 2006, he appeared in his 100th UEFA match, against Sporting Clube de Portugal.  Zanetti celebrated his 600th match for Inter on 24 September 2008 with a 1-0 win over newly promoted Lecce. Minutes before the match, he was presented with a commemorative plate by former vice-captain Ivan Cordoba to mark the occasion.  Though Zanetti is more often classified as a defender, he played mostly in midfield during the first half of the 2008-09 season. For the last several weeks of October 2008, with Inter coach Jose Mourinho facing a midfield crisis due to injuries to key midfielders Esteban Cambiasso and Sulley Muntari, he was moved again to the midfield for the matches against Genoa and Fiorentina. During that period, Mourinho played him in the midfield due to the presence of Maicon, Lucio, Walter Samuel and Cristian Chivu in the back four.  The 2009-10 season began well for Zanetti and Inter, especially after a 4-0 thrashing of crosstown rivals Milan in the Derby della Madonnina. In the match against Genoa on 17 October, he started off the counter-attack that led to Inter's second goal after dispossessing a Genoa player. Inter became the first team of the season to win by a five-goal margin. On 24 October, he reached Giacinto Facchetti's record of 476 Serie A appearances when he turned out for the match against Catania, which ended in a 2-1 win for the Nerazzurri. He also currently holds a club record of 149 consecutive appearances.  Inter won the 2010 Champions League final 2-0 against Bayern Munich on 22 May 2010. This was Zanetti's 700th appearance for Inter, and it made him the first player to captain an Italian club to a treble of the Scudetto, Coppa Italia and Champions League.

who did they beat by 5 goals
The 2009-10 season began well for Zanetti and Inter, especially after a 4-0 thrashing of crosstown rivals Milan in