The former Gunners boss insists Giroud - who scored 105 goals for Arsenal - still has plenty to offer at Stamford Bridge.
"I said that many times as well [as in the Premier League] in the French national team there is always a debate about him," Wenger told CBS Sports.
"But Olivier Giroud has - apart from his footballing qualities - he has an absolutely strong mentality and strong motivational level and has qualities that nobody else has.
"He can always be a resource inside a club even when he doesn't start the game and has an immaculate mentality.
"He is a real team player what is not always the case for strikers and overall I think he is an exceptional personality. And that's why every time you think he's disappeared, he bounces back.
"There's no coincidence, he has over 100 caps for France. Nobody gives you 100 caps to please you."