An Argentine defender, Gabriel Alejandro Paletta began his football career in the Youth Divisions of Club Atletico Banfield. He reached the first team in 2005, when Banfield qualified for the Copa Libertadores. Paletta was brought into the first team squad and made his debut against Independiente Medellin, a Colombian club. He impressed many with his talent, but could not play any further with the team as he was called into the Argentine U-20 team, for the 2005 FIFA World Youth Championship.
In 2006, Paletta signed a four year deal with Liverpool, and joined the club for a fee of ₤2 million. He became the second Argentine to join Liverpool, the first being Mauricio Pellegrino. He made his debut for the club against Wrexham, in a pre-season friendly, and then for a League Cup match against Reading, which they won 4-3, including a goal by Paletta.
After one year with Liverpool, Paletta returned to Argentina to play for Boca in the 2007 FIFA Club World Cup Final, which Boca lost to Italian giants, AC Milan, 4-2. In the first half of 2008 Copa Revancha, he went on to score against River Plate, arch rivals of Boca and also played in the 2008 Copa Libertadores, reaching the semi-finals with the team.
Paletta suffered an injury to the cruciate ligament in August 2008, and was out of the game for six months. At the international level, he started all seven games of the 2005 FIFA World Youth Championships, which Argentina eventually won.