Hesse, Kehl joined
Hannover 96's youth system in 1996 at the age of 15, going on to appear in two
2. Bundesliga seasons with the first team.
 In the 2000 summer he signed for
SC Freiburg in the
Bundesliga, making his debut in the competition on 12 August by playing the full 90 minutes in a 4–0 home win against
VfB Stuttgart, and scoring his first goal on 12 December of that year to help to a 2–1 away success over
Under legendary manager
Volker Finke, Kehl featured mostly as a
, helping the
Black Forest club
qualify to the
UEFA Cup in
his first season but
suffering relegation in his second. He was no longer part of the squad, however, as he had left in the 2002 January
transfer window to
Borussia Dortmund, who went on to win the championship with 15 games and one goal from the player; previously, in the 2001 summer, he controversially agreed basic terms with
FC Bayern Munich, and even accepted an advanced payment of 1.5 million
Deutsche Mark, which was returned in November as Bayern threatened to take legal action.
During his tenure with Dortmund, Kehl was more often than not a starter. He contributed with 12 matches in the
2002–03 edition of the
UEFA Champions League to help his team reach the second group phase, and amassed 61 league appearances from 2004 to 2006 in back-to-back seventh-place finishes.
In the first day of the
2006–07 campaign, Kehl injured his left knee in a challenge with Bayern's
Hasan Salihamidžić, going on to be sidelined for several months and only recovering fully in the start of
2008–09, when he was made
by new coach
 He eventually relapsed on his condition,
 also losing his importance in the starting XI after the emergence of
Sven Bender and
On 27 July 2013, Kehl played the second half of the
DFL-Supercup contest against Bayern Munich,
Bender in an eventual
 In September, he was put out of action for another lengthy period, after injuring his ankle in training.
Kehl began hinting at retirement in March 2014, shortly after having agreed to a one-year extension to his contract.
 The 35-year-old confirmed it at the end of the
 after having taken part in 21 games to help Borussia come from behind in the table and finally
qualify to the Europa League.