It was Ajaccio who had the first effort on goal and Adrian Mutu finished well to make it 1-0.
Valenciennes looked to equalise and had a chance through Remi Gomis, who missed the target on 34 minutes.
Minutes later, Anthony Le Tallec had another chance for the away side, though his effort was off-target.
Valenciennes came close to an equaliser on 59 minutes when Opa Nguette saw his goal-bound header blocked.
Valenciennes' chances of a comeback were then dealt a blow when the referee gave Brou Angoua a straight red card after 64 minutes.
Matters got worse for the away side when Ajaccio were awarded a penalty on 66 minutes, though Mutu missed from his spot kick.
Nguette then equalised for Valenciennes on 69 minutes to make it 1-1.