Born in Buenos Aires, Giménez started his career as a 17-year-old in the Argentine lower leagues, playing for Club Atlético San Miguel.

In 1995, he was signed by the Boca Juniors, but he only played for them for one season before being loaned out to fellow Argentine team Nueva Chicago.

In 1997, Boca Juniors sold Giménez to Swiss team FC Lugano, who in the previous season had suffered relegation.

Giménez scored his first goal for his new team in the home game in the St. Jakob-Park on 25 July in the semi-final of the competition.

He scored his first domestic league goal with the team during the 3–1 home win against the Young Boys on 11 August.

Basel won the last game of the season, on 8 May 2002, and became champions ten points clear at the top of the table.

They ended this in second position behind Valencia, but ahead of Liverpool and Spartak Moscow to advance to the second group stage.

Basel won the championship with 26 victories and seven draws, the team had suffered just three away defeats, and obtained 85 points.

[13] Basel completed all the 2004–05 Super League season's seventeen home games undefeated, winning thirteen and drawing four.

[14] One of the season's highlights for the team, was the 8–1 home win on 12 September against rivals Grasshoppers in which Giménez scored four goals.

[18] Giménez's time at Basel ended similar to that with previous team Lugano, through the back door and before a major Champions League qualifier.

[3] After a difficult year he signed a one-year loan agreement with German Bundesliga club Hertha BSC, on 4 August 2006.

It was reported that the transfer costed one million Euros and that Giménez had signed a three-year contract, which was to run until 2009, but he was sold for double that fee just one month later.