Abdennour arrived in southwestern France in the summer of 2011 from Tunisian club Etoile du Sahel, initially on a four-year contract until 2015.
But the 22-year-old has become a key player and with 18 matches played this season is viewed as one of the top central defenders in Ligue 1.
"His adaptation to L1 has been a real success and he's a player who has a great future ahead of him," predicted Toulouse coach Alain Casanova.
Toulouse moved to improve Abdennour's contract and salary amid reports of interest from top European clubs including Premier League side Arsenal.
The French club are currently eighth in the league, 16 points behind leaders Paris Saint Germain.
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