In the 2009/2010 season, Thomas Kahlenberg made the move from AJ Auxerre to VfL Wolfsburg. The 29-year-old moved to the Bundesliga as an absolutely essential element of his team in Ligue 1 but soon found himself plagued by injury.

The Dane spent four months dealing with a persistent hip problem following his transfer and then recurrent injury-related set-backs caused further difficulties for the midfielder. In 2012 he was released on loan to FC Evian but this time around, Thomas Kahlenberg is determined to make an impact in the VfL colours – a true sign of his battler's mentality.

Brøndby and Auxerre
Kahlenberg did not make his senior debut for Brøndby, until youth team coach Tom Køhlert was promoted to head coach in May 2002. On 12 May 2002, Kahlenberg made his Superliga debut against arch-rivals København, at the penultimate match of the 2001–02 season. The result was a 1–1 draw, which helped Brøndby secure the 2001–02 Danish championship on goal difference.

During his first years at Brøndby, Kahlenberg played in the central midfield, where he set up the attacks with his great technique and view for the game. In the 2004–05 season, Kahlenberg was moved out as left midfielder, following the sale of Swedish international left winger Mattias Jonson. Cutting into the field from his wide position, Kahlenberg managed to become Brøndby's 2004–05 league top goalscorer with 13 goals, leading the club in winning The Double. Kahlenberg played a combined total of 130 games for Brøndby IF, including 97 games and 28 goals in the Danish Superliga championship.

In July 2005, the French club AJ Auxerre made a transfer fee offer of £2.5 million for Kahlenberg, which Brøndby accepted. Kahlenberg signed a four-year contract with Auxerre in the top-flight Ligue 1 championship. Kahlenberg made the most assists of all players in the 2004–05 Ligue 1 championship. In his four seasons at Auxerre, Kahlenberg played 130 games and scored 19 goals in the Ligue 1.

Wolfsburg
In May 2009, Kahlenberg signed a four-year contract with the defending German champions VfL Wolfsburg for a €4 million transfer fee, effective from the end of the season. Immediately after joining Wolfsburg, Kahlenberg suffered an injury which kept him out until October 2009. He made his Fußball-Bundesliga debut for Wolfsburg in the 3–3 draw with 1. FSV Mainz 05 on 31 October.