Second-half goals from Sloan Privat and Yannis Salibur have put Guingamp into the top half of the table, after they condemned struggling Toulouse to another defeat.
EAG made their intentions clear from the start, with Privat's set piece almost creating a breakthrough inside four minutes for Jimmy Briand.
Le Tefece had chances of their own in the first half, including Martin Braithwaite's effort, which looked destined for the top corner before the intervention of Jonas Lossl with a flying stop.
Before the interval, Guingamp were awarded a penalty for Yann Bodiger's poor challenge on Marcus Coco. However, Briand's spot kick was turned away by Ali Ahamada as Toulouse stayed in the game.
EAG would not be denied for long and on 59 minutes, they finally broke the resolve of the visitors as Salibur's cross was headed home by Privat.
Guingamp doubled their lead with 20 minutes left when Salibur bent a low free kick into the corner of Ahamada's net.
The visitors' miserable evening worsened after Jean-Armel Kana Biyik was sent off for violent conduct, following his tackle on Coco.
