Abdennour was born in Sousse, Tunisia. His preferred position is a left winger, although he regularly plays at left-back. He started his career at Etoile Sportive du Sahel in 2008. During his spell with Etoile, he was a fan favourite despite being one of the youngest players in the team. In the 2008–09 season he scored five goals for his club, but they missed on the title and finished third.
On 14 January 2010, Abdennour signed a half year loan deal with SV Werder Bremen which will initially saw him stay at the club until the end of the 2009–10 season. Bremen had the contract option to sign him permanently. Abdennour made six appearances for Werder Bremen. Following the 2009–10 season, Werder Bremen did not take up the option to sign Abdennour and he returned to Étoile.
In July, 2011, Abdennour signed a four year contract with the Ligue 1 side Toulouse. In February 2012, Toulouse extended this, tying the Tunisian to a deal running until 2016.
On 31 January 2014, Abdennour joined the league rivals Monaco on a loan deal. After impressing during a loan spell, he signed a four-year deal with Monaco on 4 July 2014.